Transmitting/receiving system and method of processing broadcast signal in transmitting/receiving system

ABSTRACT

A receiving system and a method of processing broadcast signal are disclosed herein. The receiving system includes a signal receiving unit, a signaling decoder, a block decoder, and an RS frame decoder. When a parade change command ordering parade change from a first parade to a second parade is generated, the signal receiving unit receives a broadcast signal including data groups of the second parade starting from a generation point of the parade change command. The signaling decoder decodes signaling information included in the data groups and outputting RS frame-related information. The block decoder performs turbo-decoding in block units on data of a portion included in the data groups. And the RS frame decoder inserts null data in data positions of a portion included in non-received data group within an RS frame of the second parade, while configuring the RS frame of the second parade by collecting data of the turbo-decoded portions based upon the RS frame-related information. The RS frame decoder also performs CRC-decoding by indicating the existence of errors on CRC error flags of each row including the null data within the RS frame, and performs RS-decoding on the CRC-decoded RS frame.

This application claims the benefit of U.S. Provisional Application No.61/112,197, filed on Nov. 7, 2008, which is hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital broadcasting system fortransmitting and receiving digital broadcast signal, and moreparticularly, to a transmitting system for processing and transmittingdigital broadcast signal, and a receiving system for receiving andprocessing digital broadcast signal and, a method of processing data inthe transmitting system and the receiving system.

2. Discussion of the Related Art

The Vestigial Sideband (VSB) transmission mode, which is adopted as thestandard for digital broadcasting in North America and the Republic ofKorea, is a system using a single carrier method. Therefore, thereceiving performance of the digital broadcast receiving system may bedeteriorated in a poor channel environment. Particularly, sinceresistance to changes in channels and noise is more highly required whenusing portable and/or mobile broadcast receivers, the receivingperformance may be even more deteriorated when transmitting mobileservice data by the VSB transmission mode.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a transmitting systemand a receiving system and a method of processing broadcast signal thatsubstantially obviate one or more problems due to limitations anddisadvantages of the related art.

An object of the present invention is to provide a transmitting systemand a receiving system and a method of processing broadcast signal thatare highly resistant to channel changes and noise.

Another object of the present invention is to provide a transmittingsystem and a receiving system and a method of processing broadcastsignal that can enhance the receiving performance of the receivingsystem by performing additional encoding on mobile service data and bytransmitting the processed data to the receiving system.

Another object of the present invention is to provide a transmittingsystem and a receiving system and a method of processing broadcastsignal that can also enhance the receiving performance of the receivingsystem by inserting known data already known in accordance with apre-agreement between the receiving system and the transmitting systemin a predetermined region within a data region.

Another object of the present invention is to provide a receiving systemand a method for processing a broadcast signal that can reduce theparade change time, when a parade change command to change from oneparade to another parade is generated.

A further object of the present invention is to provide a receivingsystem and a method for processing a broadcast signal that can ensurecontinuity in a mobile service that is provided to a user, when a paradechange command to change from one parade to another parade is generated.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, adigital broadcast transmitting system may include a service multiplexerand a transmitter. The service multiplexer may multiplex mobile servicedata and main service data at a predetermined data rate and may transmitthe multiplexed data to the transmitter. The transmitter may performadditional encoding on the mobile service data being transmitted fromthe service multiplexer. The transmitter may also group a plurality ofadditionally encoded mobile service data packets so as to form a datagroup. The transmitter may multiplex mobile service data packetsincluding mobile service data and main service data packets includingmain service data and may transmit the multiplexed data packets to areceiving system.

Herein, the data group may be divided into a plurality of regionsdepending upon a degree of interference of the main service data. Also,a long known data sequence may be periodically inserted in regionswithout interference of the main service data. Also, a receiving systemaccording to an embodiment of the present invention may be used fordemodulating and channel equalizing the known data sequence.

In another aspect of the present invention, a receiving system includesa signal receiving unit, a signaling decoder, a block decoder, and an RSframe decoder. When a parade change command ordering parade change froma first parade to a second parade is generated, the signal receivingunit receives a broadcast signal including data groups of the secondparade starting from a generation point of the parade change command,while receiving the broadcast signal including a transmission frametransmitting the first and second parades. The signaling decoder decodessignaling information included in the data groups and outputting RSframe-related information. The block decoder performs turbo-decoding inblock units on data of a portion included in the data groups. And the RSframe decoder inserts null data in data positions of a portion includedin non-received data group within an RS frame of the second parade,while configuring the RS frame of the second parade by collecting dataof the turbo-decoded portions based upon the RS frame-relatedinformation. The RS frame decoder performs CRC-decoding by indicatingthe existence of errors on CRC error flags of each row including thenull data within the RS frame, and performs RS-decoding on theCRC-decoded RS frame.

Herein, the RS frame decoder may count a number of CRC error flagsindicating the existence of an error, among the CRC error flagscorresponding to each row within the RS frame, thereby estimating anumber of CRC errors. The RS frame decoder may also generate areliability map indicating reliability information on each data withinthe RS frame, and wherein the reliability information corresponding tothe null data is marked to be unreliable.

When the number of CRC errors is less than or equal to a maximum numberof errors correctable by RS erasure decoding, the RS frame decoder mayperform RS erasure decoding on all columns of the RS frame. And, whenthe number of CRC errors is greater than a maximum number of errorscorrectable by RS erasure decoding, the RS frame decoder may refer tothe reliability information of the reliability map, and perform any oneof general RS-decoding and RS erasure decoding for each column of the RSframe.

When the parade change command ordering the parade change from the firstparade to the second parade is generated, the signal receiving unit mayreceive a broadcast signal including data groups of the second paradefrom a next transmission frame. The RS frame decoder may collect data ofa portion included in data groups of the first parade, the first paradebeing received until the generation point of the parade change commandand being turbo-decoded, so as to configure an RS frame, and insert nulldata in data positions of a portion included in non-received data groupswithin the RS frame of the first parade. The RS frame decoder may alsoperform CRC-decoding by indicating the existence of errors on CRC errorflags of each row including the null data within the RS frame of thefirst parade, and perform RS-decoding on the CRC-decoded RS frame.

In another aspect of the present invention, a method for processing abroadcast signal of a receiving system includes, when a parade changecommand ordering parade change from a first parade to a second parade isgenerated, receiving a broadcast signal including data groups of thesecond parade starting from a generation point of the parade changecommand, while receiving the broadcast signal including a transmissionframe transmitting the first and second parades, decoding signalinginformation included in the data groups and outputting RS frame-relatedinformation, performing turbo-decoding in block units on data of aportion included in the data groups, and inserting null data in datapositions of a portion included in non-received data group within an RSframe of the second parade, while configuring the RS frame of the secondparade by collecting data of the turbo-decoded portions based upon theRS frame-related information, performing CRC-decoding by indicating theexistence of errors on CRC error flags of each row including the nulldata within the RS frame, and performing RS-decoding on the CRC-decodedRS frame.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a structure of a M/H frame for transmitting andreceiving mobile service data according to the present invention;

FIG. 2 illustrates an exemplary structure of a VSB frame;

FIG. 3 illustrates a mapping example of the positions to which the first4 slots of a sub-frame are assigned with respect to a VSB frame in aspace region;

FIG. 4 illustrates a mapping example of the positions to which the first4 slots of a sub-frame are assigned with respect to a VSB frame in atime region;

FIG. 5 illustrates an alignment of data after being data interleaved andidentified;

FIG. 6 illustrates an enlarged portion of the data group shown in FIG. 5for a better understanding of the present invention;

FIG. 7 illustrates an alignment of data before being data interleavedand identified;

FIG. 8 illustrates an enlarged portion of the data group shown in FIG. 7for a better understanding of the present invention;

FIG. 9 illustrates an exemplary assignment order of data groups beingassigned to one of 5 sub-frames according to the present invention;

FIG. 10 illustrates an example of assigning a single parade to an M/Hframe according to the present invention;

FIG. 11 illustrates an example of assigning 3 parades to an M/H frameaccording to the present invention;

FIG. 12 illustrates an example of expanding the assignment process of 3parades to 5 sub-frames within an M/H frame;

FIG. 13 illustrates a data transmission structure according to anembodiment of the present invention, wherein signaling data are includedin a data group so as to be transmitted;

FIG. 14 illustrates a block diagram showing a general structure of atransmitting system according to an embodiment of the present invention;

FIG. 15 is a diagram illustrating an example of RS frame according tothe present invention;

FIG. 16 is a diagram illustrating a structure of an M/H header within anM/H service data packet according to the present invention;

FIG. 17( a) and FIG. 17( b) are diagrams illustrating another example ofRS frame according to the present invention;

FIG. 18 illustrates a block diagram showing an example of a servicemultiplexer of FIG. 14;

FIG. 19 illustrates a block diagram showing an embodiment of atransmitter of FIG. 14;

FIG. 20 illustrates a block diagram showing an example of apre-processor of FIG. 19;

FIG. 21 illustrates a conceptual block diagram of the

M/H frame encoder of FIG. 20;

FIG. 22 illustrates a detailed block diagram of an RS frame encoder ofFIG. 21;

FIG. 23( a) and FIG. 23( b) illustrate a process of one or two RS framebeing divided into several portions, based upon an RS frame mode value,and a process of each portion being assigned to a corresponding regionwithin the respective data group;

FIG. 24( a) to FIG. 24( c) illustrate error correction encoding anderror detection encoding processes according to an embodiment of thepresent invention;

FIG. 25( a) to FIG. 25( d) illustrate an example of performing a rowpermutation (or interleaving) process in super frame units according tothe present invention;

FIG. 26( a) and FIG. 26( b) illustrate an example which a paradeconsists of two RS frames;

FIG. 27( a) and FIG. 27( b) illustrate an exemplary process of dividingan RS frame for configuring a data group according to the presentinvention;

FIG. 28 illustrates a block diagram of a block processor according to anembodiment of the present invention;

FIG. 29 illustrates a detailed block diagram of a convolution encoder ofthe block processor;

FIG. 30 illustrates a symbol interleaver of the block processor;

FIG. 31 illustrates a block diagram of a group formatter according to anembodiment of the present invention;

FIG. 32 illustrates a block diagram of a trellis encoder according to anembodiment of the present invention;

FIG. 33 illustrates an example of assigning signaling information areaaccording to an embodiment of the present invention;

FIG. 34 illustrates a detailed block diagram of a signaling encoderaccording to the present invention;

FIG. 35 illustrates an example of a syntax structure of TPC dataaccording to the present invention;

FIG. 36 illustrates an example of a transmission scenario of the TPCdata and the FIC data level according to the present invention;

FIG. 37 illustrates an example of power saving of in a receiver whentransmitting 3 parades to an M/H frame level according to the presentinvention;

FIG. 38 illustrates an example of a training sequence at the byte levelaccording to the present invention;

FIG. 39 illustrates an example of a training sequence at the symbolaccording to the present invention;

FIG. 40 illustrates a block diagram of a receiving system according toan embodiment of the present invention;

FIG. 41 is a block diagram showing an example of a demodulating unit inthe receiving system;

FIG. 42 is a block diagram showing an example of an operation controllerof FIG. 41;

FIG. 43 illustrates an example of linear interpolation according to thepresent invention;

FIG. 44 illustrates an example of linear extrapolation according to thepresent invention;

FIG. 45 illustrates a block diagram of a channel equalizer according toan embodiment of the present invention;

FIG. 46 illustrates a block diagram of a block decoder according to anembodiment of the present invention;

FIG. 47( a) and FIG. 47( b) illustrate an exemplary process ofconfiguring one or two RS frame by collecting a plurality of portionsaccording to the present invention;

FIG. 48 and FIG. 49 illustrate process steps of error correctiondecoding according to an embodiment of the present invention;

FIG. 50 illustrates an example of a generation point of a parade changecommand within the M/H frame according to the present invention;

FIG. 51 illustrates an RS frame configuration according to anotherembodiment of the present invention;

FIG. 52 illustrates an exemplary CRC decoding result, when data of afirst portion have not been received in the RS frame of FIG. 50;

FIG. 53 illustrates an exemplary CRC decoding result, when data of afirst portion and data of a second portion have not been received in theRS frame of FIG. 50;

FIG. 54 illustrates a flow chart showing the RS frame decoding processin accordance with the parade change command according to an embodimentof the present invention;

FIG. 55 illustrates another example of a generation point of a paradechange command within the M/H frame according to the present invention;

FIG. 56 illustrates an exemplary CRC decoding result, when data of afifth portion have not been received in the RS frame of FIG. 50;

FIG. 57 to FIG. 64 illustrate an exemplary of a data group formatrepresented using numbers before (prior) data interleaving according tothe present invention;

FIG. 65 to FIG. 75 illustrate an exemplary of a data group formatrepresented using numbers before (prior) data interleaving according tothe present invention;

FIG. 76 illustrates an example of a training sequence represented usingnumbers at the byte level according to the present invention; and

FIG. 77 illustrates an example of a training sequence represented usingnumbers at the symbol according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts. In addition,although the terms used in the present invention are selected fromgenerally known and used terms, some of the terms mentioned in thedescription of the present invention have been selected by the applicantat his or her discretion, the detailed meanings of which are describedin relevant parts of the description herein. Furthermore, it is requiredthat the present invention is understood, not simply by the actual termsused but by the meaning of each term lying within.

Among the terms used in the description of the present invention, mainservice data correspond to data that can be received by a fixedreceiving system and may include audio/video (A/V) data. Morespecifically, the main service data may include A/V data of highdefinition (HD) or standard definition (SD) levels and may also includediverse data types required for data broadcasting. Also, the known datacorrespond to data pre-known in accordance with a pre-arranged agreementbetween the receiving system and the transmitting system.

Additionally, among the terms used in the present invention, “M/H (orMH)” corresponds to the initials of “mobile” and “handheld” andrepresents the opposite concept of a fixed-type system. Furthermore, theM/H service data may include at least one of mobile service data andhandheld service data, and will also be referred to as “mobile servicedata” for simplicity. Herein, the mobile service data not onlycorrespond to M/H service data but may also include any type of servicedata with mobile or portable characteristics. Therefore, the mobileservice data according to the present invention are not limited only tothe M/H service data.

The above-described mobile service data may correspond to data havinginformation, such as program execution files, stock information, and soon, and may also correspond to A/V data. Most particularly, the mobileservice data may correspond to A/V data having lower resolution andlower data rate as compared to the main service data. For example, if anA/V codec that is used for a conventional main service corresponds to aMPEG-2 codec, a MPEG-4 advanced video coding (AVC) or scalable videocoding (SVC) having better image compression efficiency may be used asthe A/V codec for the mobile service. Furthermore, any type of data maybe transmitted as the mobile service data. For example, transportprotocol expert group (TPEG) data for broadcasting real-timetransportation information may be transmitted as the main service data.

Also, a data service using the mobile service data may include weatherforecast services, traffic information services, stock informationservices, viewer participation quiz programs, real-time polls andsurveys, interactive education broadcast programs, gaming services,services providing information on synopsis, character, background music,and filming sites of soap operas or series, services providinginformation on past match scores and player profiles and achievements,and services providing information on product information and programsclassified by service, medium, time, and theme enabling purchase ordersto be processed. Herein, the present invention is not limited only tothe services mentioned above.

In the present invention, the transmitting system provides backwardcompatibility in the main service data so as to be received by theconventional receiving system. Herein, the main service data and themobile service data are multiplexed to the same physical channel andthen transmitted.

Furthermore, the transmitting system according to the present inventionperforms additional encoding on the mobile service data and inserts thedata already known by the receiving system and transmitting system(e.g., known data), thereby transmitting the processed data.

Therefore, when using the transmitting system according to the presentinvention, the receiving system may receive the mobile service dataduring a mobile state and may also receive the mobile service data withstability despite various distortion and noise occurring within thechannel.

M/H Frame Structure

In the embodiment of the present invention, the mobile service data arefirst multiplexed with main service data in M/H frame units and, then,modulated in a VSB mode and transmitted to the receiving system.

At this point, one M/H frame consists of K1 number of sub-frames,wherein one sub-frame includes K2 number of slots. Also, each slot maybe configured of K3 number of data packets. In the embodiment of thepresent invention, K1 will be set to 5, K2 will be set to 16, and K3will be set to 156 (i.e., K1=5, K2=16, and K3=156). The values for K1,K2, and K3 presented in this embodiment either correspond to valuesaccording to a preferred embodiment or are merely exemplary. Therefore,the above-mentioned values will not limit the scope of the presentinvention.

FIG. 1 illustrates a structure of an M/H frame for transmitting andreceiving mobile service data according to the present invention. In theexample shown in FIG. 1, one M/H frame consists of 5 sub-frames, whereineach sub-frame includes 16 slots. In this case, the M/H frame accordingto the present invention includes 5 sub-frames and 80 slots. Also, in apacket level, one slot is configured of 156 data packets (i.e.,transport stream packets), and in a symbol level, one slot is configuredof 156 data segments. Herein, the size of one slot corresponds to onehalf (½) of a VSB field. More specifically, since one 207-byte datapacket has the same amount of data as a data segment, a data packetprior to being interleaved may also be used as a data segment.

At this point, two VSB fields are grouped to form a VSB frame.

FIG. 2 illustrates an exemplary structure of a VSB frame, wherein oneVSB frame consists of 2 VSB fields (i.e., an odd field and an evenfield). Herein, each VSB field includes a field synchronization segmentand 312 data segments.

The slot corresponds to a basic time period for multiplexing the mobileservice data and the main service data. Herein, one slot may eitherinclude the mobile service data or be configured only of the mainservice data.

If one M/H frame is transmitted during one slot, the first 118 datapackets within the slot correspond to a data group. And, the remaining38 data packets become the main service data packets. In anotherexample, when no data group exists in a slot, the corresponding slot isconfigured of 156 main service data packets.

Meanwhile, when the slots are assigned to a VSB frame, an offset existsfor each assigned position.

FIG. 3 illustrates a mapping example of the positions to which the first4 slots of a sub-frame are assigned with respect to a VSB frame in aspace region. And, FIG. 4 illustrates a mapping example of the positionsto which the first 4 slots of a sub-frame are assigned with respect to aVSB frame in a time region.

Referring to FIG. 3 and FIG. 4, a 38^(th) data packet (TS packet #37) ofa 1^(st) slot (Slot #0) is mapped to the 1^(st) data packet of an oddVSB field. A 38^(th) data packet (TS packet #37) of a 2^(nd) slot (Slot#1) is mapped to the 157^(th) data packet of an odd VSB field. Also, a38^(th) data packet (TS packet #37) of a 3^(rd) slot (Slot #2) is mappedto the 1^(st) data packet of an even VSB field. And, a 38^(th) datapacket (TS packet #37) of a 4^(th) slot (Slot #3) is mapped to the157^(th) data packet of an even VSB field. Similarly, the remaining 12slots within the corresponding sub-frame are mapped in the subsequentVSB frames using the same method.

Meanwhile, one data group may be divided into at least one or morehierarchical regions. And, depending upon the characteristics of eachhierarchical region, the type of mobile service data being inserted ineach region may vary. For example, the data group within each region maybe divided (or categorized) based upon the receiving performance.

In an example given in the present invention, a data group is dividedinto regions A, B, C, and D in a data configuration after datainterleaving.

FIG. 5 illustrates an alignment of data after being data interleaved andidentified. FIG. 6 illustrates an enlarged portion of the data groupshown in FIG. 5 for a better understanding of the present invention.FIG. 7 illustrates an alignment of data before being data interleavedand identified. And, FIG. 8 illustrates an enlarged portion of the datagroup shown in FIG. 7 for a better understanding of the presentinvention. More specifically, a data structure identical to that shownin FIG. 5 is transmitted to a receiving system. In other words, one datapacket is data-interleaved so as to be scattered to a plurality of datasegments, thereby being transmitted to the receiving system. FIG. 5illustrates an example of one data group being scattered to 170 datasegments. At this point, since one 207-byte packet has the same amountof data as one data segment, the packet that is not yet processed withdata-interleaving may be used as the data segment.

FIG. 5 shows an example of dividing a data group prior to beingdata-interleaved into 10 M/H blocks (i.e., M/H block (B1) to M/H block10 (B10)). In this example, each M/H block has the length of 16segments. Referring to FIG. 5, only the RS parity data are allocated toa portion of 5 segments before the M/H block 1 (B1) and 5 segmentsbehind the M/H block 10 (B10). The RS parity data are excluded inregions A to D of the data group.

More specifically, when it is assumed that one data group is dividedinto regions A, B, C, and D, each M/H block may be included in any oneof region A to region D depending upon the characteristic of each M/Hblock within the data group. At this point, according to an embodimentof the present invention, each M/H block may be included in any one ofregion A to region D based upon an interference level of main servicedata.

Herein, the data group is divided into a plurality of regions to be usedfor different purposes. More specifically, a region of the main servicedata having no interference or a very low interference level may beconsidered to have a more resistant (or stronger) receiving performanceas compared to regions having higher interference levels. Additionally,when using a system inserting and transmitting known data in the datagroup, wherein the known data are known based upon an agreement betweenthe transmitting system and the receiving system, and when consecutivelylong known data are to be periodically inserted in the mobile servicedata, the known data having a predetermined length may be periodicallyinserted in the region having no interference from the main service data(i.e., a region wherein the main service data are not mixed). However,due to interference from the main service data, it is difficult toperiodically insert known data and also to insert consecutively longknown data to a region having interference from the main service data.

Referring to FIG. 5, M/H block 4 (B4) to M/H block 7 (B7) correspond toregions without interference of the main service data. M/H block 4 (B4)to M/H block 7 (B7) within the data group shown in FIG. 5 correspond toa region where no interference from the main service data occurs. Inthis example, a long known data sequence is inserted at both thebeginning and end of each M/H block. In the description of the presentinvention, the region including M/H block 4 (B4) to M/H block 7 (B7)will be referred to as “region A (=B4+B5+B6+B7)”. As described above,when the data group includes region A having a long known data sequenceinserted at both the beginning and end of each M/H block, the receivingsystem is capable of performing equalization by using the channelinformation that can be obtained from the known data. Therefore, thestrongest equalizing performance may be yielded (or obtained) from oneof region A to region D.

In the example of the data group shown in FIG. 5, M/H block 3 (B3) andM/H block 8 (B8) correspond to a region having little interference fromthe main service data. Herein, a long known data sequence is inserted inonly one side of each M/H block B3 and B8. More specifically, due to theinterference from the main service data, a long known data sequence isinserted at the end of M/H block 3 (B3), and another long known datasequence is inserted at the beginning of M/H block 8 (B8). In thepresent invention, the region including M/H block 3 (B3) and M/H block 8(B8) will be referred to as “region B(=B3+B8)”. As described above, whenthe data group includes region B having a long known data sequenceinserted at only one side (beginning or end) of each M/H block, thereceiving system is capable of performing equalization by using thechannel information that can be obtained from the known data. Therefore,a stronger equalizing performance as compared to region C/D may beyielded (or obtained).

Referring to FIG. 5, M/H block 2 (B2) and M/H block 9 (B9) correspond toa region having more interference from the main service data as comparedto region B. A long known data sequence cannot be inserted in any sideof M/H block 2 (B2) and M/H block 9 (B9). Herein, the region includingM/H block (B2) and M/H block 9 (B9) will be referred to as “regionC(=B2+B9)”. Finally, in the example shown in FIG. 5, M/H block 1 (B1)and M/H block 10 (B10) correspond to a region having more interferencefrom the main service data as compared to region C. Similarly, a longknown data sequence cannot be inserted in any side of M/H block 1 (B1)and M/H block 10 (B10).

Herein, the region including M/H block 1 (B1) and M/H block 10 (B10)will be referred to as “region D (=B1+B10)”. Since region C/D is spacedfurther apart from the known data sequence, when the channel environmentundergoes frequent and abrupt changes, the receiving performance ofregion C/D may be deteriorated.

FIG. 7 illustrates a data structure prior to data interleaving. Morespecifically, FIG. 7 illustrates an example of 118 data packets beingallocated to a data group. FIG. 7 shows an example of a data groupconsisting of 118 data packets, wherein, based upon a reference packet(e.g., a 1^(st) packet (or data segment) or 157^(th) packet (or datasegment) after a field synchronization signal), when allocating datapackets to a VSB frame, 37 packets are included before the referencepacket and 81 packets (including the reference packet) are includedafterwards.

In other words, with reference to FIG. 5, a field synchronization signalis placed (or assigned) between M/H block 2 (B2) and M/H block 3 (B3).Accordingly, this indicates that the slot has an off-set of 37 datapackets with respect to the corresponding VSB field.

FIG. 57 to FIG. 64 illustrate an exemplary data group format representedusing numbers before (prior) data interleaving. In FIG. 57 to FIG. 64,the 207 variable bytes of each 208-byte MPEG-2 transport stream packetare shown. The initial MPEG-2 sync byte of each packet is not shown.Referring to FIG. 57 to FIG. 64, number 0 corresponds to main servicedata (i.e., normal VSB data), number 1 corresponds to signaling data (orsignling bytes or signaling information), number 2 corresponds to dummydata bytes, number 3 corresponds to trellis initialization bytes, number4 corresponds to MPEG header, number 5 corresponds to known (training)data sequence, number 6 corresponds to mobile service data (i.e., M/HData), and number 9 corresponds to RS parity bytes.

FIG. 65 to FIG. 75 illustrate an exemplary data group format representedusing numbers after data interleaving. In FIG. 65 to FIG. 75, the 207variable bytes of each 208-byte MPEG-2 transport stream packet areshown. The initial MPEG-2 sync byte of each packet is not shown. In adata group containing a field synchronization segment, the fieldsyncronization segment shall be inserted between data group segments #36and #37; i.e., 37 data group segments precede a data fieldsyncronization segment. Referring to FIG. 65 to FIG. 75, number 0corresponds to main service data (i.e., normal VSB data), number 1corresponds to signaling data (or signling bytes or signalinginformation), number 2 corresponds to dummy data bytes, number 3corresponds to trellis initialization bytes, number 4 corresponds toMPEG header, number 5 corresponds to known (training) data sequence,number 6 corresponds to mobile service data (i.e., M/H Data), and number9 corresponds to RS parity bytes.

The size of the data groups, number of hierarchical regions within thedata group, the size of each region, the number of M/H blocks includedin each region, the size of each M/H block, and so on described aboveare merely exemplary. Therefore, the present invention will not belimited to the examples described above.

FIG. 9 illustrates an exemplary assignment order of data groups beingassigned to one of 5 sub-frames, wherein the 5 sub-frames configure anM/H frame. For example, the method of assigning data groups may beidentically applied to all M/H frames or differently applied to each M/Hframe. Furthermore, the method of assigning data groups may beidentically applied to all sub-frames or differently applied to eachsub-frame. At this point, when it is assumed that the data groups areassigned using the same method in all sub-frames of the correspondingM/H frame, the total number of data groups being assigned to an M/Hframe is equal to a multiple of ‘5’.

According to the embodiment of the present invention, a plurality ofconsecutive data groups is assigned to be spaced as far apart from oneanother as possible within the M/H frame. Thus, the system can becapable of responding promptly and effectively to any burst error thatmay occur within a sub-frame.

For example, when it is assumed that 3 data groups are assigned to asub-frame, the data groups are assigned to a 1^(st) slot (Slot #0), a5^(th) slot (Slot #4), and a 9^(th) slot (Slot #8) in the sub-frame,respectively. FIG. 9 illustrates an example of assigning 16 data groupsin one sub-frame using the above-described pattern (or rule). In otherwords, each data group is serially assigned to 16 slots corresponding tothe following numbers: 0, 8, 4, 12, 1, 9, 5, 13, 2, 10, 6, 14, 3, 11, 7,and 15. Equation 1 below shows the above-described rule (or pattern) forassigning data groups in a sub-frame.

$\begin{matrix}{{{Herein},\;{j = {( {{4i} + 0} )\mspace{14mu}{mod}\mspace{14mu} 16}}}{{0 = {{0\mspace{14mu}{if}\mspace{14mu} i} < 4}},{0 = {{2\mspace{14mu}{else}\mspace{14mu}{if}\mspace{14mu} i} < 8}},{0 = {{1{\mspace{11mu}\;}{else}\mspace{14mu}{if}\mspace{14mu} i} < 12}},{0 = {3\mspace{14mu}{{else}.}}}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Herein, j indicates the slot number within a sub-frame. The value of jmay range from 0 to 15 (i.e., 0≦j≦15). Also, value of i indicates thedata group number. The value of i may range from 0 to 15 (i.e., 0≦i≦15).

In the present invention, a collection of data groups included in an M/Hframe will be referred to as a “parade”. Based upon the RS frame mode,the parade transmits data of at least one specific RS frame.

The mobile service data within one RS frame may be assigned either toall of regions A/B/C/D within the corresponding data group, or to atleast one of regions A/B/C/D. In the embodiment of the presentinvention, the mobile service data within one RS frame may be assignedeither to all of regions A/B/C/D, or to at least one of regions A/B andregions C/D. If the mobile service data are assigned to the latter case(i.e., one of regions A/B and regions C/D), the RS frame being assignedto regions A/B and the RS frame being assigned to regions C/D within thecorresponding data group are different from one another.

In the description of the present invention, the RS frame being assignedto regions A/B within the corresponding data group will be referred toas a “primary RS frame”, and the RS frame being assigned to regions C/Dwithin the corresponding data group will be referred to as a “secondaryRS frame”, for simplicity. Also, the primary RS frame and the secondaryRS frame form (or configure) one parade. More specifically, when themobile service data within one RS frame are assigned either to all ofregions A/B/C/D within the corresponding data group, one paradetransmits one RS frame. In this case, also the RS frame will be referredto as a “primary RS frame”. Conversely, when the mobile service datawithin one RS frame are assigned either to at least one of regions A/Band regions C/D, one parade may transmit up to 2 RS frames.

More specifically, the RS frame mode indicates whether a paradetransmits one RS frame, or whether the parade transmits two RS frames.Table 1 below shows an example of the RS frame mode.

TABLE 1 RS frame mode (2 bits) Description 00 There is only one primaryRS frame for all group regions 01 There are two separate RS frames.Primary RS frame for group regions A and B Secondary RS frame for groupregions C and D 10 Reserved 11 Reserved

Table 1 illustrates an example of allocating 2 bits in order to indicatethe RS frame mode. For example, referring to Table 1, when the RS framemode value is equal to ‘00’, this indicates that one parade transmitsone RS frame. And, when the RS frame mode value is equal to ‘01’, thisindicates that one parade transmits two RS frames, i.e., the primary RSframe and the secondary RS frame. More specifically, when the RS framemode value is equal to ‘01’, data of the primary RS frame for regionsA/B are assigned and transmitted to regions A/B of the correspondingdata group. Similarly, data of the secondary RS frame for regions C/Dare assigned and transmitted to regions C/D of the corresponding datagroup.

As described in the assignment of data groups, the parades are alsoassigned to be spaced as far apart from one another as possible withinthe sub-frame. Thus, the system can be capable of responding promptlyand effectively to any burst error that may occur within a sub-frame.

Furthermore, the method of assigning parades may be identically appliedto all sub-frames or differently applied to each sub-frame. According tothe embodiment of the present invention, the parades may be assigneddifferently for each M/H frame and identically for all sub-frames withinan M/H frame. More specifically, the M/H frame structure may vary by M/Hframe units. Thus, an ensemble rate may be adjusted on a more frequentand flexible basis.

FIG. 10 illustrates an example of multiple data groups of a singleparade being assigned (or allocated) to an M/H frame. More specifically,FIG. 10 illustrates an example of a plurality of data groups included ina single parade, wherein the number of data groups included in asub-frame is equal to ‘3’, being allocated to an M/H frame. Referring toFIG. 10, 3 data groups are sequentially assigned to a sub-frame at acycle period of 4 slots. Accordingly, when this process is equallyperformed in the 5 sub-frames included in the corresponding M/H frame,15 data groups are assigned to a single M/H frame. Herein, the 15 datagroups correspond to data groups included in a parade. Therefore, sinceone sub-frame is configured of 4 VSB frame, and since 3 data groups areincluded in a sub-frame, the data group of the corresponding parade isnot assigned to one of the 4 VSB frames within a sub-frame.

For example, when it is assumed that one parade transmits one RS frame,and that a RS frame encoder located in a later block performsRS-encoding on the corresponding RS frame, thereby adding 24 bytes ofparity data to the corresponding RS frame and transmitting the processedRS frame, the parity data occupy approximately 11.37% (=24/(187+24)×100)of the total code word length. Meanwhile, when one sub-frame includes 3data groups, and when the data groups included in the parade areassigned, as shown in FIG. 10, a total of 15 data groups form an RSframe. Accordingly, even when an error occurs in an entire data groupdue to a burst noise within a channel, the percentile is merely 6.67% (=1/15×100). Therefore, the receiving system may correct all errors byperforming an erasure RS decoding process. More specifically, when theerasure RS decoding is performed, a number of channel errorscorresponding to the number of RS parity bytes may be corrected. Bydoing so, the receiving system may correct the error of at least onedata group within one parade. Thus, the minimum burst noise lengthcorrectable by a RS frame is over 1 VSB frame.

Meanwhile, when data groups of a parade are assigned as described above,either main service data may be assigned between each data group, ordata groups corresponding to different parades may be assigned betweeneach data group. More specifically, data groups corresponding tomultiple parades may be assigned to one M/H frame.

Basically, the method of assigning data groups corresponding to multipleparades is very similar to the method of assigning data groupscorresponding to a single parade. In other words, data groups includedin other parades that are to be assigned to an M/H frame are alsorespectively assigned according to a cycle period of 4 slots.

At this point, data groups of a different parade may be sequentiallyassigned to the respective slots in a circular method. Herein, the datagroups are assigned to slots starting from the ones to which data groupsof the previous parade have not yet been assigned.

For example, when it is assumed that data groups corresponding to aparade are assigned as shown in FIG. 10, data groups corresponding tothe next parade may be assigned to a sub-frame starting either from the12^(th) slot of a sub-frame. However, this is merely exemplary. Inanother example, the data groups of the next parade may also besequentially assigned to a different slot within a sub-frame at a cycleperiod of 4 slots starting from the 3^(rd) slot.

FIG. 11 illustrates an example of transmitting 3 parades (Parade #0,Parade #1, and Parade #2) to an M/H frame. More specifically, FIG. 11illustrates an example of transmitting parades included in one of 5sub-frames, wherein the 5 sub-frames configure one M/H frame.

When the 1^(st) parade (Parade #0) includes 3 data groups for eachsub-frame, the positions of each data groups within the sub-frames maybe obtained by substituting values ‘0’ to ‘2’ for i in Equation 1. Morespecifically, the data groups of the 1^(st) parade (Parade #0) aresequentially assigned to the 1^(st), 5^(th), and 9^(th) slots (Slot #0,Slot #4, and Slot #8) within the sub-frame. Also, when the 2^(nd) paradeincludes 2 data groups for each sub-frame, the positions of each datagroups within the sub-frames may be obtained by substituting values ‘3’and ‘4’ for i in Equation 1.

More specifically, the data groups of the 2^(nd) parade (Parade #1) aresequentially assigned to the 2^(nd) and 12^(th) slots (Slot #3 and Slot#11) within the sub-frame.

Finally, when the 3^(rd) parade includes 2 data groups for eachsub-frame, the positions of each data groups within the sub-frames maybe obtained by substituting values ‘5’ and ‘6’ for i in Equation 1. Morespecifically, the data groups of the 3^(rd) parade (Parade #2) aresequentially assigned to the 7^(th) and 11^(th) slots (Slot #6 and Slot#10) within the sub-frame.

As described above, data groups of multiple parades may be assigned to asingle M/H frame, and, in each sub-frame, the data groups are seriallyallocated to a group space having 4 slots from left to right. Therefore,a number of groups of one parade per sub-frame (NOG) may correspond toany one integer from ‘1’ to ‘8’. Herein, since one M/H frame includes 5sub-frames, the total number of data groups within a parade that can beallocated to an M/H frame may correspond to any one multiple of ‘5’ranging from ‘5’ to ‘40’.

FIG. 12 illustrates an example of expanding the assignment process of 3parades, shown in FIG. 11, to 5 sub-frames within an M/H frame.

FIG. 13 illustrates a data transmission structure according to anembodiment of the present invention, wherein signaling data are includedin a data group so as to be transmitted.

As described above, an M/H frame is divided into 5 sub-frames. Datagroups corresponding to a plurality of parades co-exist in eachsub-frame. Herein, the data groups corresponding to each parade aregrouped by M/H frame units, thereby configuring a single parade.

The data structure shown in FIG. 13 includes 3 parades (parade #0,parade #1, parade #2). Also, a predetermined portion of each data group(i.e., 37 bytes/data group) is used for delivering (or sending) FICinformation associated with mobile service data, wherein the FICinformation is separately encoded from the RS-encoding process. The FICregion assigned to each data group consists of one FIC segments.

Meanwhile, the concept of an M/H ensemble is applied in the embodimentof the present invention, thereby defining a collection (or group) ofservices. Each M/H ensemble carries the same QoS and is coded with thesame FEC code. Also, each M/H ensemble has the same unique identifier(i.e., ensemble ID) and corresponds to consecutive RS frames.

As shown in FIG. 13, the FIC segment corresponding to each data groupdescribed service information of an M/H ensemble to which thecorresponding data group belongs.

General Description of the Transmitting System

FIG. 14 illustrates a block diagram showing a general structure of adigital broadcast transmitting system according to an embodiment of thepresent invention.

Herein, the digital broadcast transmitting includes a servicemultiplexer 100 and a transmitter 200. Herein, the service multiplexer100 is located in the studio of each broadcast station, and thetransmitter 200 is located in a site placed at a predetermined distancefrom the studio. The transmitter 200 may be located in a plurality ofdifferent locations. Also, for example, the plurality of transmittersmay share the same frequency. And, in this case, the plurality oftransmitters receives the same signal. This corresponds to datatransmission using Single Frequency Network (SFN). Accordingly, in thereceiving system, a channel equalizer may compensate signal distortion,which is caused by a reflected wave, so as to recover the originalsignal. In another example, the plurality of transmitters may havedifferent frequencies with respect to the same channel. This correspondsto data transmission using Multi Frequency Network (MFN).

A variety of methods may be used for data communication each of thetransmitters, which are located in remote positions, and the servicemultiplexer. For example, an interface standard such as a synchronousserial interface for transport of MPEG-2 data (SMPTE-310M). In theSMPTE-310M interface standard, a constant data rate is decided as anoutput data rate of the service multiplexer. For example, in case of the8VSB mode, the output data rate is 19.39 Mbps, and, in case of the 16VSBmode, the output data rate is 38.78 Mbps. Furthermore, in theconventional 8VSB mode transmitting system, a transport stream (TS)packet having a data rate of approximately 19.39 Mbps may be transmittedthrough a single physical channel. Also, in the transmitting systemaccording to the present invention provided with backward compatibilitywith the conventional transmitting system, additional encoding isperformed on the mobile service data. Thereafter, the additionallyencoded mobile service data are multiplexed with the main service datato a TS packet form, which is then transmitted. At this point, the datarate of the multiplexed TS packet is approximately 19.39 Mbps.

At this point, the service multiplexer 100 receives at least one type ofmain service data and table information (e.g., PSI/PSIP table data) foreach main service and encapsulates the received data into a transportstream (TS) packet.

Also, according to an embodiment of the present invention, the servicemultiplexer 100 receives at least one type of mobile service data andtable information (e.g., PSI/PSIP table data) for each mobile serviceand encapsulates the received data into a transport stream (TS) packet.

According to another embodiment of the present invention, the servicemultiplexer 100 receives a RS frame, which is configured of at least onetype of mobile service data and table information for each mobileservice, and encapsulates the received RS frame data into mobile servicedata packets of a transport stream (TS) packet format.

And, the service multiplexer 100 multiplexes the encapsulated TS packetsfor main service and the encapsulated TS packets for mobile servicebased upon a predetermined multiplexing rule, thereby outputting themultiplexed TS packets to the transmitter 200.

At this point, the RS frame has the size of N(row)×187 (column), asshown in FIG. 15. Herein, N represents the length of a row (i.e., numberof columns), and 187 corresponds to the length of a column (i.e., numberof rows.

In the present invention, each row configured of N bytes will bereferred to as an M/H service data packet for simplicity. The M/Hservice data packet may be configured of a 2-byte M/H header and a(N−2)-byte M/H payload. Herein, the assigning 2 bytes to the M/H headerregion is merely exemplary. The above-described configuration may bealtered by the system designer and will, therefore, not be limited onlyto the example presented in the description of the present invention.

The RS frame is generated by collecting (or gathering) table informationand/or mobiles service data collectively corresponding to a size of(N−2) (row)×187 (column) bytes.

According to an embodiment of the present invention, the mobile servicedata has the form of an IP datagram. Herein, the RS frame may includetable information and IP datagram corresponding to at least one mobileservice. Also, one RS frame may include table information and IPdatagram corresponding to one or more mobile services. For example, IPdatagram and table information of two different types of mobile servicedata, such as news service (e.g., IP datagram for mobile service 1) andstock information service (e.g., IP datagram for mobile service 2), maybe included in a single RS frame.

More specifically, either table information of a section structure or anIP datagram of a mobile service data may be assigned to an M/H payloadwithin an M/H service data packet configuring the RS frame.Alternatively, either an IP datagram of table information or an IPdatagram of a mobile service data may be assigned to an M/H payloadwithin an M/H service data packet configuring the RS frame.

At this point, the size of the M/H service data packet including the M/Hheader may not be equal to N bytes.

In this case, stuffing bytes may be assigned to the surplus (orremaining) payload region within the corresponding M/H service datapacket. For example, after assigning program table information to an M/Hservice data packet, when the length of the corresponding M/H servicedata packet including the M/H header is equal to (N−20) bytes, stuffingbytes may be assigned to the remaining 20-byte region.

The RS frame may be assigned to at least one of regions A/B/C/D within adata group by the transmitter. In the description of the presentinvention, when the RS frame is assigned to regions A/B/C/D within thedata group, or when the RS frame is assigned to regions A/B, the RSframe will be referred to as a primary RS frame. Alternatively, when theRS frame is assigned to regions C/D, the RS frame will be referred to asa secondary RS frame.

FIG. 16 is a diagram illustrating examples of fields allocated to theM/H header region within the M/H service data packet according to thepresent invention. Examples of the fields include type_indicator field,error_indicator field, stuff_indicator field, and pointer field.

The type_indicator field can allocate 3 bits, for example, andrepresents a type of data allocated to payload within the correspondingM/H service data packet. In other words, the type_indicator fieldindicates whether data of the payload is IP datagram or program tableinformation. At this time, each data type constitutes one logicalchannel. In the logical channel which transmits the IP datagram, severalmobile services are multiplexed and then transmitted. Each mobileservice undergoes demultiplexing in the IP layer.

The error_indicator field can allocate 1 bit, for example, andrepresents whether the corresponding M/H service data packet has anerror. For example, if the error_indicator field has a value of 0, itmeans that there is no error in the corresponding M/H service datapacket. If the error_indicator field has a value of 1, it means thatthere may be an error in the corresponding M/H service data packet.

The stuff_indicator field can allocate 1 bit, for example, andrepresents whether stuffing byte exists in payload of the correspondingM/H service data packet. For example, if the stuff_indicator field has avalue of 0, it means that there is no stuffing byte in the correspondingM/H service data packet. If the stuff_indicator field has a value of 1,it means that stuffing byte exists in the corresponding M/H service datapacket.

The pointer field can allocate 11 bits, for example, and representsposition information where new data (i.e., new signaling information ornew IP datagram) starts in the corresponding M/H service data packet.

For example, if IP datagram for mobile service 1 and IP datagram formobile service 2 are allocated to the first M/H service data packetwithin the RS frame as illustrated in FIG. 15, the pointer field valuerepresents the start position of the IP datagram for mobile service 2within the M/H service data packet.

Also, if there is no new data in the corresponding M/H service datapacket, the corresponding field value is expressed as a maximum valueexemplarily. According to the embodiment of the present invention, since11 bits are allocated to the pointer field, if 2047 is expressed as thepointer field value, it means that there is no new data in the packet.The point where the pointer field value is 0 can be varied depending onthe type_indicator field value and the stuff_indicator field value.

It is to be understood that the order, the position, and the meaning ofthe fields allocated to the header within the M/H service data packetillustrated in FIG. 16 are exemplarily illustrated for understanding ofthe present invention. Since the order, the position and the meaning ofthe fields allocated to the header within the M/H service data packetand the number of additionally allocated fields can easily be modifiedby those skilled in the art, the present invention will not be limitedto the above example.

FIG. 17( a) and FIG. 17( b) illustrate another examples of RS frameaccording to the present invention. FIG. 17( a) illustrates an exampleof primary RS frame to be allocated to regions A/B within the datagroup, and FIG. 17( b) illustrates an example of secondary RS frame tobe allocated to regions C/D within the data group.

In FIG. 17( a) and FIG. 17( b), a column length (i.e., the number ofrows) of the RS frame to be allocated to the regions A/B and a columnlength (i.e., the number of rows) of the RS frame to be allocated to theregions C/D are 187 equally. However, row lengths (i.e, the number ofcolumns) may be different from each other.

According to the embodiment of the present invention, when the rowlength of the primary RS frame to be allocated to the regions A/B withinthe data group is N1 bytes and the row length of the secondary RS frameto be allocated to the regions C/D within the data group is N2 bytes, acondition of N1>N2 is satisfied. In this case, N1 and N2 can be varieddepending on the transmission parameter or a region of the data group,to which the corresponding RS frame will be transmitted.

For convenience of the description, each row of the N1 and N2 bytes willbe referred to as the M/H service data packet. The M/H service datapacket within the RS frame to be allocated to the regions A/B within thedata group can be comprised of M/H header of 2 bytes and payload of N1−2bytes. Also, the M/H service data packet within the RS frame to beallocated to the regions C/D within the data group can be comprised ofM/H header of 2 bytes and payload of N2−2 bytes.

In the present invention, the primary RS frame for the regions A/Bwithin the data group and the secondary RS frame for the regions C/Dwithin the data group can include at least one of program tableinformation and IP datagram. Also, one RS frame can include IP datagramcorresponding to one or more mobile services.

Corresponding parts of FIG. 15 can be applied to the other parts, whichare not described in FIG. 17( a) and FIG. 17( b).

Meanwhile, the value of N, which corresponds to the number of columnswithin an RS frame, can be decided according to Equation 2.

$\begin{matrix}{N = {\lfloor \frac{5 \times {NoG} \times {PL}}{187 + P} \rfloor - 2}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

Herein, NoG indicates the number of data groups assigned to a sub-frame.PL represents the number of SCCC payload data bytes assigned to a datagroup. And, P signifies the number of RS parity data bytes added to eachcolumn of the RS frame. Finally, └X┘ is the greatest integer that isequal to or smaller than X.

More specifically, in Equation 2, PL corresponds to the length of an RSframe portion. The value of PL is equivalent to the number of SCCCpayload data bytes that are assigned to the corresponding data group.Herein, the value of PL may vary depending upon the RS frame mode, SCCCblock mode, and SCCC outer code mode. Table 2 to Table 5 belowrespectively show examples of PL values, which vary in accordance withthe RS frame mode, SCCC block mode, and SCCC outer code mode. The SCCCblock mode and the SCCC outer code mode will be described in detail in alater process.

TABLE 2 SCCC outer code mode for for for for Region A Region B Region CRegion D PL 00 00 00 00 9624 00 00 00 01 9372 00 00 01 00 8886 00 00 0101 8634 00 01 00 00 8403 00 01 00 01 8151 00 01 01 00 7665 00 01 01 017413 01 00 00 00 7023 01 00 00 01 6771 01 00 01 00 6285 01 00 01 01 603301 01 00 00 5802 01 01 00 01 5550 01 01 01 00 5064 01 01 01 01 4812Others Reserved

Table 2 shows an example of the PL values for each data group within anRS frame, wherein each PL value varies depending upon the SCCC outercode mode, when the RS frame mode value is equal to ‘00’, and when theSCCC block mode value is equal to ‘00’. For example, when it is assumedthat each SCCC outer code mode value of regions A/B/C/D within the datagroup is equal to ‘00’ (i.e., the block processor 302 of a later blockperforms encoding at a coding rate of 1/2), the PL value within eachdata group of the corresponding RS frame may be equal to 9624 bytes.More specifically, 9624 bytes of mobile service data within one RS framemay be assigned to regions A/B/C/D of the corresponding data group.

TABLE 3 SCCC outer code mode PL 00 9624 01 4812 Others Reserved

Table 3 shows an example of the PL values for each data group within anRS frame, wherein each PL value varies depending upon the SCCC outercode mode, when the RS frame mode value is equal to ‘00’, and when theSCCC block mode value is equal to ‘01’.

TABLE 4 SCCC outer code mode for Region A for Region B PL 00 00 7644 0001 6423 01 00 5043 01 01 3822 Others Reserved

Table 4 shows an example of the PL values for each data group within aprimary RS frame, wherein each PL value varies depending upon the SCCCouter code mode, when the RS frame mode value is equal to ‘01’, and whenthe SCCC block mode value is equal to ‘00’. For example, when each SCCCouter code mode value of regions A/B is equal to ‘00’, 7644 bytes ofmobile service data within a primary RS frame may be assigned to regionsA/B of the corresponding data group.

TABLE 5 SCCC outer code mode for Region C for Region D PL 00 00 1980 0001 1728 01 00 1242 01 01  990 Others Reserved

Table 5 shows an example of the PL values for each data group within asecondary RS frame, wherein each PL value varies depending upon the SCCCouter code mode, when the RS frame mode value is equal to ‘01’, and whenthe SCCC block mode value is equal to ‘00’. For example, when each SCCCouter code mode value of regions C/D is equal to ‘00’, 1980 bytes ofmobile service data within a secondary RS frame may be assigned toregions C/D of the corresponding data group.

Service Multiplexer

FIG. 18 illustrates a block diagram showing an example of the servicemultiplexer. The service multiplexer includes a controller 110 forcontrolling the overall operations of the service multiplexer, a tableinformation generator 120 for the main service, a null packet generator130, an OM packet encapsulator 140, a mobile service multiplexer 150,and a transport multiplexer 160.

The transport multiplexer 160 may include a main service multiplexer 161and a transport stream (TS) packet multiplexer 162.

Referring to FIG. 18, at least one type of compression-encoded mainservice data and table data generated from the table informationgenerator 120 for the main services are inputted to the main servicemultiplexer 161 of the transport multiplexer 160. According to theembodiment of the present invention, the table information generator 120generates PSI/PSIP table data, which is configured in the form of anMPEG-2 private section.

The main service multiplexer 161 respectively encapsulates each of themain service data and the PSI/PSIP table data, which are being inputted,to MPEG-2 TS packet formats, thereby multiplexing the encapsulated TSpackets and outputting the multiplexed packets to the TS packetmultiplexer 162. Herein, the data packet being outputted from the mainservice multiplexer 161 will hereinafter be referred to as a mainservice data packet for simplicity.

The mobile service multiplexer 150 receives and respectivelyencapsulates at least one type of compression-encoded mobile servicedata and the table information (e.g., PSI/PSIP table data) for mobileservices to MPEG-2 TS packet formats. Then, the mobile servicemultiplexer 150 multiplexes the encapsulated TS packets, therebyoutputting the multiplexed packets to the TS packet multiplexer 162.Hereinafter, the data packet being outputted from the mobile servicemultiplexer 150 will be referred to as a mobile service data packet forsimplicity.

Alternatively, the mobile service multiplexer 150 receives andencapsulates an RS frame, which is generated by using at least one typeof compression-encoded mobile service data and the table information formobile services, to MPEG-2 TS packet formats. Then, the mobile servicemultiplexer 150 multiplexes the encapsulated TS packets, therebyoutputting the multiplexed packets to the TS packet multiplexer 162.Hereinafter, the data packet being outputted from the mobile servicemultiplexer 150 will be referred to as a mobile service data packet forsimplicity.

According to an embodiment of the present invention, the mobile servicemultiplexer 150 encapsulates an RS frame, which is inputted in any oneof the formats shown in FIG. 15, FIG. 17A, or FIG. 17B, to a TS packetformat.

At this point, the transmitter 200 requires identification informationin order to identify and process the main service data packet and themobile service data packet. Herein, the identification information mayuse values pre-decided in accordance with an agreement between thetransmitting system and the receiving system, or may be configured of aseparate set of data, or may modify predetermined location value with inthe corresponding data packet.

As an example of the present invention, a different packet identifier(PID) may be assigned to identify each of the main service data packetand the mobile service data packet. More specifically, by assigning aPID, which does not use for the main service data packet, to the mobileservice data packet, the transmitter 200 refers to a PID of data packetinputted, thereby can identify each of the main service data packet andthe mobile service data packet.

In another example, by modifying a synchronization data byte within aheader of the mobile service data, the service data packet may beidentified by using the synchronization data byte value of thecorresponding service data packet. For example, the synchronization byteof the main service data packet directly outputs the value decided bythe ISO/IEC 13818-1 standard (i.e., 0x47) without any modification. Thesynchronization byte of the mobile service data packet modifies andoutputs the value, thereby identifying the main service data packet andthe mobile service data packet. Conversely, the synchronization byte ofthe main service data packet is modified and outputted, whereas thesynchronization byte of the mobile service data packet is directlyoutputted without being modified, thereby enabling the main service datapacket and the mobile service data packet to be identified.

A plurality of methods may be applied in the method of modifying thesynchronization byte. For example, each bit of the synchronization bytemay be inversed, or only a portion of the synchronization byte may beinversed.

As described above, any type of identification information may be usedto identify the main service data packet and the mobile service datapacket. Therefore, the scope of the present invention is not limitedonly to the example set forth in the description of the presentinvention.

Meanwhile, a transport multiplexer used in the conventional digitalbroadcasting system may be used as the transport multiplexer 160according to the present invention. More specifically, in order tomultiplex the mobile service data and the main service data and totransmit the multiplexed data, the data rate of the main service islimited to a data rate of (19.39−K) Mbps. Then, K Mbps, whichcorresponds to the remaining data rate, is assigned as the data rate ofthe mobile service. Thus, the transport multiplexer which is alreadybeing used may be used as it is without any modification.

Herein, the transport multiplexer 160 multiplexes the main service datapacket being outputted from the main service multiplexer 161 and themobile service data packet being outputted from the mobile servicemultiplexer 150. Thereafter, the transport multiplexer 160 transmits themultiplexed data packets to the transmitter 200.

However, in some cases, the output data rate of the mobile servicemultiplexer 150 may not be equal to K Mbps. For example, when theservice multiplexer 100 assigns K Mbps of the 19.39 Mbps to the mobileservice data, and when the remaining (19.39−K) Mbps is, therefore,assigned to the main service data, the data rate of the mobile servicedata that are multiplexed by the service multiplexer 100 actuallybecomes lower than K Mbps. This is because, in case of the mobileservice data, the pre-processor of the transmitting system performsadditional encoding, thereby increasing the amount of data. Eventually,the data rate of the mobile service data, which may be transmitted fromthe service multiplexer 100, becomes smaller than K Mbps.

For example, since the pre-processor of the transmitter performs anencoding process on the mobile service data at a coding rate of at least1/2, the amount of the data outputted from the pre-processor isincreased to more than twice the amount of the data initially inputtedto the pre-processor. Therefore, the sum of the data rate of the mainservice data and the data rate of the mobile service data, both beingmultiplexed by the service multiplexer 100, becomes either equal to orsmaller than 19.39 Mbps.

In order to set the final output data rate of the mobile servicemultiplexer 150 to K Mbps, the service multiplexer 100 of the presentinvention may perform various exemplary operations.

According to an embodiment of the present invention, the null packetgenerator 130 may generate a null data packet, which is then outputtedto the mobile service multiplexer 150. Thereafter, the mobile servicemultiplexer 150 may multiplex the null data packet and the mobileservice data packets, so as to set the output data rate to K Mbps.

At this point, the null data packet is transmitted to the transmitter200, thereby being discarded. More specifically, the null data packet isnot transmitted to the receiving system. In order to do so,identification information for identifying the null data is alsorequired. Herein, the identification information for identifying thenull data may also use a value pre-decided based upon an agreementbetween the transmitting system and the receiving system and may also beconfigured of a separate set of data. And, the identificationinformation for identifying the null data may also change apredetermined position value within the null data packet and use thechanged value. For example, the null packet generator 130 may modify (orchange) a synchronization byte value within the header of the null datapacket, thereby using the changed value as the identificationinformation. Alternatively, the transport_error_indicator flag may beset to ‘1’, thereby being used as the identification information.According to the embodiment of the present invention, thetransport_error_indicator flag within the header of the null data packetis used as the identification information for identifying the null datapacket. In this case, the transport_error_indicator flag of the nulldata packet is set to ‘1’, and the transport_error_indicator flag foreach of the other remaining data packets is reset to ‘0’, so that thenull data packet can be identified (or distinguished).

More specifically, when the null packet generator 130 generated a nulldata packet, and if, among the fields included in the header of the nulldata packet, the transport_error_indicator flag is set to ‘1’ and thentransmitted, the transmitter 200 may identify and discard the null datapacket corresponding to the transport_error_indicator flag.

Herein, any value that can identify the null data packet may be used asthe identification information for identifying the null data packet.Therefore, the present invention will not be limited only to the exampleproposed in the description of the present invention.

As another example of setting (or matching) the final output data rateof the mobile service multiplexer 150 to K Mbps, an operations andmaintenance (OM) packet (also referred to as OMP) may be used. In thiscase, the mobile service multiplexer 150 may multiplex the mobileservice data packet, the null data packet, and the OM packet, so as toset the output data rate to K Mbps.

Meanwhile, signaling data, such as transmission parameters, are requiredfor enabling the transmitter 200 to process the mobile service data.

According to an embodiment of the present invention, the transmissionparameter is inserted in the payload region of the OM packet, therebybeing transmitted to the transmitter.

At this point, in order to enable the transmitter 200 to identify theinsertion of the transmission parameter in the OM packet, identificationinformation that can identify the insertion of the transmissionparameter in the type field of the corresponding OM packet (i.e.,OM_type field).

More specifically, an operations and maintenance packet

(OMP) is defined for the purpose of operating and managing thetransmitting system. For example, the OMP is configured in an MPEG-2 TSpacket format, and the value of its respective PID is equal to ‘0x1FFA’.The OMP consists of a 4-byte header and a 184-byte payload. Among the184 bytes, the first byte corresponds to the OM_type field indicatingthe type of the corresponding OM packet (OMP). And, the remaining 183bytes correspond to an OM_payload field, wherein actual data areinserted.

According to the present invention, among the reserved field values ofthe OM_type field, a pre-arranged value is used, thereby being capableof indicating that a transmission parameter has been inserted in thecorresponding OM packet. Thereafter, the transmitter 200 may locate (oridentify) the corresponding OMP by referring to the respective PID.Subsequently, by parsing the OM_type field within the OMP, thetransmitter 200 may be able to know (or recognize) whether or not atransmission parameter has been inserted in the corresponding OM packet.

The transmission parameters that can be transmitted to the OM packetinclude M/H frame information (e.g., M/H frame_index), FIC information(e.g., next_FIC_version_number), parade information (e.g.,number_of_parades, parade_id, parade_repetition_cycle, and ensemble_id),group information (e.g., number_of_group and start_group_number), SCCCinformation (e.g., SCCC_block_mode and SCCC_outer_code_mode), RS frameinformation (e.g., RS_Frame_mode and RS_frame_continuity_counter), RSencoding information (e.g., RS_code_mode), and so on.

At this point, the OM packet in which the transmission parameter isinserted may be periodically generated by a constant cycle, so as to bemultiplexed with the mobile service data packet.

The multiplexing rules and the generation of null data packets of themobile service multiplexer 150, the main service multiplexer 161, andthe TS packet multiplexer 160 are controlled by the controller 110.

The TS packet multiplexer 162 multiplexes a data packet being outputtedfrom the main service multiplexer 161 at (19.39−K) Mbps with a datapacket being outputted from the mobile service multiplexer 150 at KMbps. Thereafter, the TS packet multiplexer 162 transmits themultiplexed data packet to the transmitter 200 at a data rate of 19.39Mbps.

Transmitter

FIG. 19 illustrates a block diagram showing an example of thetransmitter 200 according to an embodiment of the present invention.Herein, the transmitter 200 includes a controller 201, a demultiplexer210, a packet jitter mitigator 220, a pre-processor 230, a packetmultiplexer 240, a post-processor 250, a synchronization (sync)multiplexer 260, and a transmission unit 270.

Herein, when a data packet is received from the service multiplexer 100,the demultiplexer 210 should identify whether the received data packetcorresponds to a main service data packet, a mobile service data packet,a null data packet, or an OM packet.

For example, the demultiplexer 210 uses the PID within the received datapacket so as to identify the main service data packet, the mobileservice data packet, and the null data packet. Then, the demultiplexer210 uses a transport_error_indicator field to identify the null datapacket.

If an OM packet is included in the received data packet, the OM packetmay identify using the PID within the received data packet. And by usingthe OM_type field included in the identified OM packet, thedemultiplexer 210 may be able to know whether or not a transmissionparameter is included in the payload region of the corresponding OMpacket and, then, received.

The main service data packet identified by the demultiplexer 210 isoutputted to the packet jitter mitigator 220, the mobile service datapacket is outputted to the pre-processor 230, and the null data packetis discarded. If the transmission parameter is included in the OMpacket, the corresponding transmission parameter is extracted, so as tobe outputted to the corresponding blocks. Thereafter, the OM packet isdiscarded. According to an embodiment of the present invention, thetransmission parameter extracted from the OM packet is outputted to thecorresponding blocks through the controller 201.

The pre-processor 230 performs an additional encoding process of themobile service data included in the service data packet, which isdemultiplexed and outputted from the demultiplexer 210. Thepre-processor 230 also performs a process of configuring a data group sothat the data group may be positioned at a specific place in accordancewith the purpose of the data, which are to be transmitted on atransmission frame. This is to enable the mobile service data to respondswiftly and strongly against noise and channel changes. Thepre-processor 230 may also refer to the transmission parameter extractedin the OM packet when performing the additional encoding process.

Also, the pre-processor 230 groups a plurality of mobile service datapackets to configure a data group. Thereafter, known data, mobileservice data, RS parity data, and MPEG header are allocated topre-determined regions within the data group.

Pre-Processor within Transmitter

FIG. 20 illustrates a block diagram showing the structure of apre-processor 230 according to the present invention. Herein, thepre-processor 230 includes an M/H frame encoder 301, a block processor302, a group formatter 303, a signaling encoder 304, and a packetformatter 305.

The M/H frame encoder 301, which is included in the pre-processor 230having the above-described structure, data-randomizes the mobile servicedata that are inputted to the demultiplexer 210, thereby generating a RSframe corresponding an ensemble. Then, the M/H frame encoder 301performs an encoding process for error correction in RS frame units.

The M/H frame encoder 301 may include at least one RS frame encoder.More specifically, RS frame encoders may be provided in parallel,wherein the number of RS frame encoders is equal to the number ofparades within the M/H frame. As described above, the M/H frame is abasic time cycle period for transmitting at least one parade. Also, eachparade consists of one or two RS frames.

FIG. 21 illustrates a conceptual block diagram of the

M/H frame encoder 301 according to an embodiment of the presentinvention. The M/H frame encoder 301 includes an input demultiplexer(DEMUX) 309, M number of RS frame encoders 310 to 31M-1, and an outputmultiplexer (MUX) 320. Herein, M represent the number of paradesincluded in one M/H frame.

The input demultiplexer 309 output the inputted mobile service datapacket to a corresponding RS frame encoder among M number of RS frameencoders in ensemble units.

At this point, the ensemble may be mapped to the RS frame encoder or aparade. For example, when one parade is configured of one RS frame, eachensemble, RS frame, and parade may be mapped to be in a 1:1:1 (orone-to-one-to-one) correspondence.

According to an embodiment of the present invention, each RS frameencoder groups a plurality of mobile service data packets of theensemble inputted, so as to configure an RS frame corresponding to theensemble and, then, to perform an error correction encoding process inRS frame units. Also, each RS frame encoder divides theerror-correction-encoded RS frame into a plurality of portions, in orderto assign the error-correction-encoded RS frame data to a plurality ofdata groups. Based upon the RS frame mode of Table 1, data within one RSframe may be assigned either to all of regions A/B/C/D within multipledata groups, or to at least one of regions A/B and regions C/D withinmultiple data groups.

When the RS frame mode value is equal to ‘01’, i.e., when the data ofthe primary RS frame are assigned to regions A/B of the correspondingdata group and data of the secondary RS frame are assigned to regionsC/D of the corresponding data group, each RS frame encoder generates aprimary RS frame and a secondary RS frame for each parade. Conversely,when the RS frame mode value is equal to ‘00’, when the data of theprimary RS frame are assigned to all of regions A/B/C/D, each RS frameencoder generates a RS frame (i.e., a primary RS frame) for each parade.

Also, each RS frame encoder divides each RS frame into several portions.Each portion of the RS frame is equivalent to a data amount that can betransmitted by a data group. The output multiplexer (MUX) 320multiplexes portions within M number of RS frame encoders 310 to 310M-1are multiplexed and then outputted to the block processor 302.

For example, if one parade transmits two RS frames, portions of primaryRS frames within M number of RS frame encoders 310 to 310M-1 aremultiplexed and outputted. Thereafter, portions of secondary RS frameswithin M number of RS frame encoders 310 to 310M-1 are multiplexed andtransmitted.

The input demultiplexer (DEMUX) 309 and the output multiplexer (MUX) 320operate based upon the control of the controller 201. The controller 201may provide necessary (or required) FEC modes to each RS frame encoder.The FEC mode includes the RS code mode, which will be described indetail in a later process.

FIG. 22 illustrates a detailed block diagram of an RS frame encoderamong a plurality of RS frame encoders within an M/H frame encoder.

One RS frame encoder may include a primary encoder 410 and a secondaryencoder 420. Herein, the secondary encoder 420 may or may not operatebased upon the RS frame mode. For example, when the RS frame mode valueis equal to ‘00’, as shown in Table 1, the secondary encoder 420 doesnot operate.

The primary encoder 410 may include a data randomizer 411, aReed-Solomon-cyclic redundancy check (RS-CRC) encoder (412), and a RSframe divider 413. And, the secondary encoder 420 may also include adata randomizer 421, a RS-CRC encoder (422), and a RS frame divider 423.

More specifically, the data randomizer 411 of the primary encoder 410receives mobile service data of a primary ensemble outputted from theoutput demultiplexer (DEMUX) 309. Then, after randomizing the receivedmobile service data, the data randomizer 411 outputs the randomized datato the RS-CRC encoder 412. At this point, since the data randomizer 411performs the randomizing process on the mobile service data, therandomizing process that is to be performed by the data randomizer 251of the post-processor 250 on the mobile service data may be omitted. Thedata randomizer 411 may also discard the synchronization byte within themobile service data packet and perform the randomizing process. This isan option that may be chosen by the system designer. In the examplegiven in the present invention, the randomizing process is performedwithout discarding the synchronization byte within the correspondingmobile service data packet.

The RS-CRC encoder 412 generates a RS frame corresponding to therandomized primary ensemble, and performs forward error collection(FEC)-encoding in the RS frame unit using at least one of a Reed-Solomon(RS) code and a cyclic redundancy check (CRC) code. The RS-CRC encoder412 outputs the FEC-encoded RS frame to the RS frame divider 413.

The RS-CRC encoder 412 groups a plurality of mobile service data packetsthat is randomized and inputted, so as to generate a RS frame. Then, theRS-CRC encoder 412 performs at least one of an error correction encodingprocess and an error detection encoding process in RS frame units.Accordingly, robustness may be provided to the mobile service data,thereby scattering group error that may occur during changes in afrequency environment, thereby enabling the mobile service data torespond to the frequency environment, which is extremely vulnerable andliable to frequent changes. Also, the RS-CRC encoder 412 groups aplurality of RS frame so as to generate a super frame, therebyperforming a row permutation process in super frame units. The rowpermutation process may also be referred to as a “row interleavingprocess”. Hereinafter, the process will be referred to as “rowpermutation” for simplicity. In the present invention, the rowpermutation process is optional.

More specifically, when the RS-CRC encoder 412 performs the process ofpermuting each row of the super frame in accordance with apre-determined rule, the position of the rows within the super framebefore and after the row permutation process is changed. If the rowpermutation process is performed by super frame units, and even thoughthe section having a plurality of errors occurring therein becomes verylong, and even though the number of errors included in the RS frame,which is to be decoded, exceeds the extent of being able to becorrected, the errors become dispersed within the entire super frame.Thus, the decoding ability is even more enhanced as compared to a singleRS frame.

At this point, as an example of the present invention, RS-encoding isapplied for the error correction encoding process, and a cyclicredundancy check (CRC) encoding is applied for the error detectionprocess in the RS-CRC encoder 412. When performing the RS-encoding,parity data that are used for the error correction are generated. And,when performing the CRC encoding, CRC data that are used for the errordetection are generated. The CRC data generated by CRC encoding may beused for indicating whether or not the mobile service data have beendamaged by the errors while being transmitted through the channel. Inthe present invention, a variety of error detection coding methods otherthan the CRC encoding method may be used, or the error correction codingmethod may be used to enhance the overall error correction ability ofthe receiving system.

Herein, the RS-CRC encoder 412 refers to a pre-determined transmissionparameter provided by the controller 201 so as to perform operationsincluding RS frame configuration, RS encoding, CRC encoding, super frameconfiguration, and row permutation in super frame units.

FIG. 23( a) and FIG. 23( b) illustrate a process of one or two RS framebeing divided into several portions, based upon an RS frame mode value,and a process of each portion being assigned to a corresponding regionwithin the respective data group. According to an embodiment of thepresent invention, the data assignment within the data group isperformed by the group formatter 303.

More specifically, FIG. 23( a) shows an example of the RS frame modevalue being equal to ‘00’. Herein, only the primary encoder 410 of FIG.22 operates, thereby forming one RS frame for one parade. Then, the RSframe is divided into several portions, and the data of each portion areassigned to regions A/B/C/D within the respective data group. FIG. 23(b) shows an example of the RS frame mode value being equal to ‘01’.Herein, both the primary encoder 410 and the secondary encoder 420 ofFIG. 22 operate, thereby forming two RS frames for one parade, i.e., oneprimary RS frame and one secondary RS frame. Then, the primary RS frameis divided into several portions, and the secondary RS frame is dividedinto several portions. At this point, the data of each portion of theprimary RS frame are assigned to regions A/B within the respective datagroup. And, the data of each portion of the secondary RS frame areassigned to regions C/D within the respective data group.

Detailed Description of the RS Frame

FIG. 24( a) illustrates an example of an RS frame being generated fromthe RS-CRC encoder 412 according to the present invention.

When the RS frame is generated, as shown in FIG. 24( a), the RS-CRCencoder 412 performs a (Nc,Kc)-RS encoding process on each column, so asto generate Nc−Kc(=P) number of parity bytes. Then, the RS-CRC encoder412 adds the newly generated P number of parity bytes after the verylast byte of the corresponding column, thereby generating a column of(187+P) bytes. Herein, as shown in FIG. 24( a), Kc is equal to 187(i.e., Kc=187), and Nc is equal to 187+P (i.e., Nc=187+P). Herein, thevalue of P may vary depending upon the RS code mode. Table 6 below showsan example of an RS code mode, as one of the RS encoding information.

TABLE 6 RS code Number of Parity Bytes mode RS code (P) 00 (211, 187) 2401 (223, 187) 36 10 (235, 187) 48 11 Reserved Reserved

Table 6 shows an example of 2 bits being assigned in order to indicatethe RS code mode. The RS code mode represents the number of parity bytescorresponding to the RS frame.

For example, when the RS code mode value is equal to ‘10’,(235,187)-RS-encoding is performed on the RS frame of FIG. 24( a), so asto generate 48 parity data bytes. Thereafter, the 48 parity bytes areadded after the last data byte of the corresponding column, therebygenerating a column of 235 data bytes.

When the RS frame mode value is equal to ‘00’ in Table 1 (i.e., when theRS frame mode indicates a single RS frame), only the RS code mode of thecorresponding RS frame is indicated. However, when the RS frame modevalue is equal to ‘01’ in Table 1 (i.e., when the RS frame modeindicates multiple RS frames), the RS code mode corresponding to aprimary RS frame and a secondary RS frame. More specifically, it ispreferable that the RS code mode is independently applied to the primaryRS frame and the secondary RS frame.

When such RS encoding process is performed on all N number of columns, aRS frame having the size of N(row)×(187+P) (column) bytes may begenerated, as shown in FIG. 24( b).

Each row of the RS frame is configured of N bytes. However, dependingupon channel conditions between the transmitting system and thereceiving system, error may be included in the RS frame. When errorsoccur as described above, CRC data (or CRC code or CRC checksum) may beused on each row unit in order to verify whether error exists in eachrow unit.

The RS-CRC encoder 412 may perform CRC encoding on the mobile servicedata being RS encoded so as to create (or generate) the CRC data. TheCRC data being generated by CRC encoding may be used to indicate whetherthe mobile service data have been damaged while being transmittedthrough the channel.

The present invention may also use different error detection encodingmethods other than the CRC encoding method. Alternatively, the presentinvention may use the error correction encoding method to enhance theoverall error correction ability of the receiving system.

FIG. 24( c) illustrates an example of using a 2-byte (i.e., 16-bit) CRCchecksum as the CRC data. Herein, a 2-byte CRC checksum is generated forN number of bytes of each row, thereby adding the 2-byte CRC checksum atthe end of the N number of bytes. Thus, each row is expanded to (N+2)number of bytes. Equation 3 below corresponds to an exemplary equationfor generating a 2-byte CRC checksum for each row being configured of Nnumber of bytes.g(x)=x ¹⁶ +x ¹² +x ⁵+1   Equation 3

The process of adding a 2-byte checksum in each row is only exemplary.Therefore, the present invention is not limited only to the exampleproposed in the description set forth herein. As described above, whenthe process of RS encoding and CRC encoding are completed, the(N×187)-byte RS frame is expanded to a (N+2)×(187+P)-byte RS frame.Based upon an error correction scenario of a RS frame expanded asdescribed above, the data bytes within the RS frame are transmittedthrough a channel in a row direction. At this point, when a large numberof errors occur during a limited period of transmission time, errorsalso occur in a row direction within the RS frame being processed with adecoding process in the receiving system. However, in the perspective ofRS encoding performed in a column direction, the errors are shown asbeing scattered. Therefore, error correction may be performed moreeffectively. At this point, a method of increasing the number of paritydata bytes (P) may be used in order to perform a more intense errorcorrection process. However, using this method may lead to a decrease intransmission efficiency. Therefore, a mutually advantageous method isrequired. Furthermore, when performing the decoding process, an erasuredecoding process may be used to enhance the error correctionperformance.

Additionally, the RS-CRC encoder 412 according to the present inventionalso performs a row permutation (or interleaving) process in super frameunits in order to further enhance the error correction performance whenerror correction the RS frame.

FIG. 25( a) to FIG. 25( d) illustrates an example of performing a rowpermutation process in super frame units according to the presentinvention. More specifically, G number of RS frames RS-CRC-encoded isgrouped to form a super frame, as shown in FIG. 25( a). At this point,since each RS frame is formed of (N+2)×(187+P) number of bytes, onesuper frame is configured to have the size of (N+2)×(187+P)×G bytes.

When a row permutation process permuting each row of the super frameconfigured as described above is performed based upon a pre-determinedpermutation rule, the positions of the rows prior to and after beingpermuted (or interleaved) within the super frame may be altered. Morespecifically, the i^(th) row of the super frame prior to theinterleaving process, as shown in FIG. 25( b), is positioned in thej^(th) row of the same super frame after the row permutation process, asshown in FIG. 25( c). The above-described relation between i and j canbe easily understood with reference to a permutation rule as shown inEquation 4 below.j=G(imod(187+P))+└i/(187+P)┘i=(187+P)(jmod G)+└j/G┘  Equation 4

-   -   where 0≦i, j≦(187+P)G−1; or    -   where 0≦i, j<(187+P)G

Herein, each row of the super frame is configured of (N+2) number ofdata bytes even after being row-permuted in super frame units.

When all row permutation processes in super frame units are completed,the super frame is once again divided into G number of row-permuted RSframes, as shown in FIG. 25( d), and then provided to the RS framedivider 413. Herein, the number of RS parity bytes and the number ofcolumns should be equally provided in each of the RS frames, whichconfigure a super frame. As described in the error correction scenarioof a RS frame, in case of the super frame, a section having a largenumber of error occurring therein is so long that, even when one RSframe that is to be decoded includes an excessive number of errors(i.e., to an extent that the errors cannot be corrected), such errorsare scattered throughout the entire super frame. Therefore, incomparison with a single RS frame, the decoding performance of the superframe is more enhanced.

The above description of the present invention corresponds to theprocesses of forming (or creating) and encoding an RS frame, when a datagroup is divided into regions A/B/C/D, and when data of an RS frame areassigned to all of regions A/B/C/D within the corresponding data group.More specifically, the above description corresponds to an embodiment ofthe present invention, wherein one RS frame is transmitted using oneparade. In this embodiment, the secondary encoder 420 does not operate(or is not active).

Meanwhile, 2 RS frames are transmitting using one parade, the data ofthe primary RS frame may be assigned to regions A/B within the datagroup and be transmitted, and the data of the secondary RS frame may beassigned to regions C/D within the data group and be transmitted. Atthis point, the primary encoder 410 receives the mobile service datapackets that are to be assigned to regions A/B within the data group, soas to form the primary RS frame, thereby performing RS-encoding andCRC-encoding. Similarly, the secondary encoder 420 receives the mobileservice data packets that are to be assigned to regions C/D within thedata group, so as to form the secondary RS frame, thereby performingRS-encoding and CRC-encoding. More specifically, the primary RS frameand the secondary RS frame are generated independently.

FIG. 26 illustrates examples of receiving the mobile service datapackets that are to be assigned to regions A/B within the data group, soas to form the primary RS frame, and receives the mobile service datapackets that are to be assigned to regions C/D within the data group, soas to form the secondary RS frame, thereby performing error correctionencoding and error detection encoding on each of the first and secondaryRS frames.

More specifically, FIG. 26( a) illustrates an example of the RS-CRCencoder 412 of the primary encoder 410 receiving mobile service datapackets of the primary ensemble that are to be assigned to regions A/Bwithin the corresponding data group, so as to generated an RS framehaving the size of N1(row)×187(column). Then, in this example, theprimary encoder 410 performs RS-encoding on each column of the RS framegenerated as described above, thereby adding P1 number of parity databytes in each column. Finally, the primary encoder 410 performsCRC-encoding on each row, thereby adding a 2-byte checksum in each row.

FIG. 26( b) illustrates an example of the RS-CRC encoder 422 of thesecondary encoder 420 receiving mobile service data packets of thesecondary ensemble that are to be assigned to regions C/D within thecorresponding data group, so as to generate an RS frame having the sizeof N2(row)×187(column). Then, in this example, the secondary encoder 420performs RS-encoding on each column of the RS frame generated asdescribed above, thereby adding P2 number of parity data bytes in eachcolumn. Finally, the secondary encoder 420 performs CRC-encoding on eachrow, thereby adding a 2-byte checksum in each row.

At this point, each of the RS-CRC encoders 412 and 422 may refer to apre-determined transmission parameter provided by the controller 201,the RS-CRC encoders 412 and 422 may be informed of M/H frameinformation, FIC information, RS frame information (including RS framemode information), RS encoding information (including RS code mode),SCCC information (including SCCC block mode information and SCCC outercode mode information), data group information, and region informationwithin a data group. The RS-CRC encoders 412 and 422 may refer to thetransmission parameters for the purpose of RS frame configuration, errorcorrection encoding, error detection encoding. Furthermore, thetransmission parameters should also be transmitted to the receivingsystem so that the receiving system can perform a normal decodingprocess. At this point, as an example of the present invention, thetransmission parameter is transmitted through transmission parameterchannel (TPC) to a receiving system. The TPC will be described in detailin a later.

The data of the primary RS frame, which is encoded by RS frame units androw-permuted by super frame units from the RS-CRC encoder 412 of theprimary encoder 410, are outputted to the RS frame divider 413. If thesecondary encoder 420 also operates in the embodiment of the presentinvention, the data of the secondary RS frame, which is encoded by RSframe units and row-permuted by super frame units from the RS-CRCencoder 422 of the secondary encoder 420, are outputted to the RS framedivider 423. The RS frame divider 413 of the primary encoder 410 dividesthe primary RS frame into several portions, which are then outputted tothe output multiplexer (MUX) 320. Each portion of the primary RS frameis equivalent to a data amount that can be transmitted by one datagroup. Similarly, the RS frame divider 423 of the secondary encoder 420divides the secondary RS frame into several portions, which are thenoutputted to the output multiplexer (MUX) 320.

Hereinafter, the RS frame divider 413 of the primary RS encoder 410 willnow be described in detail. Also, in order to simplify the descriptionof the present invention, it is assumed that an RS frame having the sizeof N(row)×187(column), as shown in FIG. 24( a) to FIG. 24( c), that Pnumber of parity data bytes are added to each column by RS-encoding theRS frame, and that a 2-byte checksum is added to each row byCRC-encoding the RS frame. Accordingly, the RS frame divider 413 divides(or partitions) the encoded

RS frame having the size of (N+2) (row)×187(column) into severalportions, each having the size of PL (wherein PL corresponds to thelength of the RS frame portion).

At this point, as shown in Table 2 to Table 5, the value of PL may varydepending upon the RS frame mode, SCCC block mode, and SCCC outer codermode. Also, the total number of data bytes of the RS-encoded andCRC-encoded RS frame is equal to or smaller than 5×NoG×PL. In this case,the RS frame is divided (or partitioned) into ((5×NoG)−1) number ofportions each having the size of PL and one portion having a size equalto smaller than PL. More specifically, with the exception of the lastportion of the RS frame, each of the remaining portions of the RS framehas an equal size of PL. If the size of the last portion is smaller thanPL, a stuffing byte (or dummy byte) may be inserted in order to fill (orreplace) the lacking number of data bytes, thereby enabling the lastportion of the RS frame to also be equal to PL. Each portion of an RSframe corresponds to the amount of data that are to be SCCC-encoded andmapped into a single data group of a parade.

FIG. 27( a) and FIG. 27( b) respectively illustrate examples of adding Snumber of stuffing bytes, when an RS frame having the size of (N+2)(row)×(187+P) (column) is divided into 5×NoG number of portions, eachhaving the size of PL. More specifically, the RS-encoded and CRC-encodedRS frame, shown in FIG. 27( a), is divided into several portions, asshown in FIG. 27( b). The number of divided portions at the RS frame isequal to (5×NoG). Particularly, the first ((S×NoG)−1) number of portionseach has the size of PL, and the last portion of the RS frame may beequal to or smaller than PL. If the size of the last portion is smallerthan PL, a stuffing byte (or dummy byte) may be inserted in order tofill (or replace) the lacking number of data bytes, as shown in Equation5 below, thereby enabling the last portion of the RS frame to also beequal to PL.S=(5×NoG×PL)−((N+2)×(187+P))   Equation 5

Herein, each portion including data having the size of

PL passes through the output multiplexer 320 of the M/H frame encoder301, which is then outputted to the block processor 302.

At this point, the mapping order of the RS frame portions to a parade ofdata groups in not identical with the group assignment order defined inEquation 1. When given the group positions of a parade in an M/H frame,the SCCC-encoded RS frame portions will be mapped in a time order (i.e.,in a left-to-right direction).

For example, as shown in FIG. 11, data groups of the 2^(nd) parade(Parade #1) are first assigned (or allocated) to the 13^(th) slot (Slot#12) and then assigned to the 3^(rd) slot (Slot #2). However, when thedata are actually placed in the assigned slots, the data are placed in atime sequence (or time order, i.e., in a left-to-right direction). Morespecifically, the 1^(st) data group of Parade #1 is placed in Slot #2,and the 2^(nd) data group of Parade #1 is placed in Slot #12.

Block Processor

Meanwhile, the block processor 302 performs an SCCC outer encodingprocess on the output of the M/H frame encoder 301. More specifically,the block processor 302 receives the data of each error correctionencoded portion. Then, the block processor 302 encodes the data onceagain at a coding rate of 1/H (wherein H is an integer equal to orgreater than 2 (i.e., H≧2)), thereby outputting the 1/H-rate encodeddata to the group formatter 303. According to the embodiment of thepresent invention, the input data are encoded either at a coding rate of1/2 (also referred to as “1/2-rate encoding”) or at a coding rate of 1/4(also referred to as “1/4-rate encoding”). The data of each portionoutputted from the M/H frame encoder 301 may include at least one ofpure mobile service data, RS parity data, CRC data, and stuffing data.However, in a broader meaning, the data included in each portion maycorrespond to data for mobile services. Therefore, the data included ineach portion will all be considered as mobile service data and describedaccordingly.

The group formatter 303 inserts the mobile service dataSCCC-outer-encoded and outputted from the block processor 302 in thecorresponding region within the data group, which is formed inaccordance with a pre-defined rule. Also, in association with the datadeinterleaving process, the group formatter 303 inserts various placeholders (or known data place holders) in the corresponding region withinthe data group. Thereafter, the group formatter 303 deinterleaves thedata within the data group and the place holders.

According to the present invention, with reference to data after beingdata-interleaved, as shown in FIG. 5, a data groups is configured of 10M/H blocks (B1 to B10) and divided into 4 regions (A, B, C, and D).Also, as shown in FIG. 5, when it is assumed that the data group isdivided into a plurality of hierarchical regions, as described above,the block processor 302 may encode the mobile service data, which are tobe inserted to each region based upon the characteristic of eachhierarchical region, at different coding rates. For example, the blockprocessor 302 may encode the mobile service data, which are to beinserted in region A/B within the corresponding data group, at a codingrate of 1/2. Then, the group formatter 303 may insert the 1/2-rateencoded mobile service data to region A/B. Also, the block processor 302may encode the mobile service data, which are to be inserted in regionC/D within the corresponding data group, at a coding rate of 1/4havinghigher (or stronger) error correction ability than the 1/2-coding rate.Thereafter, the group formatter 303 may insert the 1/2-rate encodedmobile service data to region C/D. In another example, the blockprocessor 302 may encode the mobile service data, which are to beinserted in region C/D, at a coding rate having higher error correctionability than the 1/4-coding rate. Then, the group formatter 303 mayeither insert the encoded mobile service data to region C/D, asdescribed above, or leave the data in a reserved region for futureusage.

According to another embodiment of the present invention, the blockprocessor 302 may perform a 1/H-rate encoding process in SCCC blockunits. Herein, the SCCC block includes at least one M/H block. At thispoint, when 1/H-rate encoding is performed in M/H block units, the M/Hblocks (B1 to B10) and the SCCC block (SCB1 to SCB10) become identicalto one another (i.e., SCB1=B1, SCB2=B2, SCB3=B3, SCB4=B4, SCB5=B5,SCB6=B6, SCB7=B7, SCB8=B8, SCB9=B9, and SCB10=B10). For example, the M/Hblock 1 (B1) may be encoded at the coding rate of 1/2, the M/H block 2(B2) may be encoded at the coding rate of 1/4, and the M/H block 3 (B3)may be encoded at the coding rate of 1/2. The coding rates are appliedrespectively to the remaining M/H blocks.

Alternatively, a plurality of M/H blocks within regions A, B, C, and Dmay be grouped into one SCCC block, thereby being encoded at a codingrate of 1/H in SCCC block units. Accordingly, the receiving performanceof region C/D may be enhanced. For example, M/H block 1 (B1) to M/Hblock 5 (B5) may be grouped into one SCCC block and then encoded at acoding rate of 1/2. Thereafter, the group formatter 303 may insert the1/2-rate encoded mobile service data to a section starting from M/Hblock 1 (B1) to M/H block 5 (B5). Furthermore, M/H block 6 (B6) to M/Hblock 10 (B10) may be grouped into one SCCC block and then encoded at acoding rate of 1/4. Thereafter, the group formatter 303 may insert the1/4-rate encoded mobile service data to another section starting fromM/H block 6 (B6) to M/H block 10 (B10). In this case, one data group mayconsist of two SCCC blocks.

According to another embodiment of the present invention, one SCCC blockmay be formed by grouping two M/H blocks. For example, M/H block 1 (B1)and M/H block 6 (B6) may be grouped into one SCCC block (SCB1).Similarly, M/H block 2 (B2) and M/H block 7 (B7) may be grouped intoanother SCCC block (SCB2). Also, M/H block 3 (B3) and M/H block 8 (B8)may be grouped into another SCCC block (SCB3). And, M/H block 4 (B4) andM/H block 9 (B9) may be grouped into another SCCC block (SCB4).Furthermore, M/H block 5 (B5) and M/H block 10 (B10) may be grouped intoanother SCCC block (SCB5). In the above-described example, the datagroup may consist of 10 M/H blocks and 5 SCCC blocks. Accordingly, in adata (or signal) receiving environment undergoing frequent and severechannel changes, the receiving performance of regions C and D, which isrelatively more deteriorated than the receiving performance of region A,may be reinforced. Furthermore, since the number of mobile service datasymbols increases more and more from region A to region D, the errorcorrection encoding performance becomes more and more deteriorated.Therefore, when grouping a plurality of M/H block to form one SCCCblock, such deterioration in the error correction encoding performancemay be reduced.

As described-above, when the block processor 302 performs encoding at a1/H-coding rate, information associated with SCCC should be transmittedto the receiving system in order to accurately recover the mobileservice data. Table 7 below shows an example of a SCCC block mode, whichindicating the relation between an M/H block and an SCCC block, amongdiverse SCCC block information.

TABLE 7 SCCC Block Mode 00 01 10 11 Description One M/H Two M/H BlockBlocks per SCCC per SCCC Block Block SCB input, SCB input, SCB M/H BlockM/H Blocks Reserved Reserved SCB1 B1 B1 + B6 SCB2 B2 B2 + B7 SCB3 B3B3 + B8 SCB4 B4 B4 + B9 SCB5 B5 B5 + B10 SCB6 B6 — SCB7 B7 — SCB8 B8 —SCB9 B9 — SCB10 B10 —

More specifically, Table 4 shows an example of 2 bits being allocated inorder to indicate the SCCC block mode. For example, when the SCCC blockmode value is equal to ‘00’, this indicates that the SCCC block and theM/H block are identical to one another. Also, when the SCCC block modevalue is equal to ‘01’, this indicates that each SCCC block isconfigured of 2 M/H blocks.

As described above, if one data group is configured of 2 SCCC blocks,although it is not indicated in Table 7, this information may also beindicated as the SCCC block mode. For example, when the SCCC block modevalue is equal to ‘10’, this indicates that each SCCC block isconfigured of 5 M/H blocks and that one data group is configured of 2SCCC blocks. Herein, the number of M/H blocks included in an SCCC blockand the position of each M/H block may vary depending upon the settingsmade by the system designer. Therefore, the present invention will notbe limited to the examples given herein. Accordingly, the SCCC modeinformation may also be expanded.

An example of a coding rate information of the SCCC block, i.e., SCCCouter code mode, is shown in Table 8 below.

TABLE 8 SCCC outer code mode (2 bits) Description 00 Outer code rate ofSCCC block is ½ rate 01 Outer code rate of SCCC block is ¼ rate 10Reserved 11 Reserved

More specifically, Table 8 shows an example of 2 bits being allocated inorder to indicate the coding rate information of the SCCC block. Forexample, when the SCCC outer code mode value is equal to ‘00’, thisindicates that the coding rate of the corresponding SCCC block is 1/2.And, when the SCCC outer code mode value is equal to ‘01’, thisindicates that the coding rate of the corresponding SCCC block is 1/4.

If the SCCC block mode value of Table 7 indicates ‘00’, the SCCC outercode mode may indicate the coding rate of each M/H block with respect toeach M/H block. In this case, since it is assumed that one data groupincludes 10 M/H blocks and that 2 bits are allocated for each SCCC blockmode, a total of 20 bits are required for indicating the SCCC blockmodes of the 10 M/H modes. In another example, when the SCCC block modevalue of Table 7 indicates ‘00’, the SCCC outer code mode may indicatethe coding rate of each region with respect to each region within thedata group. In this case, since it is assumed that one data groupincludes 4 regions (i.e., regions A, B, C, and D) and that 2 bits areallocated for each SCCC block mode, a total of 8 bits are required forindicating the SCCC block modes of the 4 regions. In another example,when the SCCC block mode value of Table 7 is equal to ‘01’, each of theregions A, B, C, and D within the data group has the same SCCC outercode mode.

Meanwhile, an example of an SCCC output block length (SOBL) for eachSCCC block, when the SCCC block mode value is equal to ‘00’, is shown inTable 9 below.

TABLE 9 SIBL ½ ¼ SCCC Block SOBL rate rate SCB1 (B1) 528 264 132 SCB2(B2) 1536 768 384 SCB3 (B3) 2376 1188 594 SCB4 (B4) 2388 1194 597 SCB5(B5) 2772 1386 693 SCB6 (B6) 2472 1236 618 SCB7 (B7) 2772 1386 693 SCB8(B8) 2508 1254 627 SCB9 (B9) 1416 708 354 SCB10 (B10) 480 240 120

More specifically, when given the SCCC output block length (SOBL) foreach SCCC block, an SCCC input block length (SIBL) for eachcorresponding SCCC block may be decided based upon the outer coding rateof each SCCC block. The SOBL is equivalent to the number of SCCC output(or outer-encoded) bytes for each SCCC block. And, the SIBL isequivalent to the number of SCCC input (or payload) bytes for each SCCCblock. Table 10 below shows an example of the SOBL and SIBL for eachSCCC block, when the SCCC block mode value is equal to ‘01’.

TABLE 10 SIBL ½ ¼ SCCC Block SOBL rate rate SCB1 (B1 + B6) 528 264 132SCB2 (B2 + B7) 1536 768 384 SCB3 (B3 + B8) 2376 1188 594 SCB4 (B4 + B9)2388 1194 597 SCB5 (B5 + B10) 2772 1386 693

In order to do so, as shown in FIG. 28, the block processor 302 includesa RS frame portion-SCCC block converter 511, a byte-bit converter 512, aconvolution encoder 513, a symbol interleaver 514, a symbol-byteconverter 515, and an SCCC block-M/H block converter 516. Theconvolutional encoder 513 and the symbol interleaver 514 are virtuallyconcatenated with the trellis encoding module in the post-processor inorder to configure an SCCC block. More specifically, the RS frameportion-SCCC block converter 511 divides the RS frame portions, whichare being inputted, into multiple SCCC blocks using the SIBL of Table 9and Table 10 based upon the RS code mode, SCCC block mode, and SCCCouter code mode. Herein, the M/H frame encoder 301 may output onlyprimary RS frame portions or both primary RS frame portions andsecondary RS frame portions in accordance with the RS frame mode.

When the RS Frame mode is set to ‘00’, a portion of the primary RS Frameequal to the amount of data, which are to be SCCC outer encoded andmapped to 10 M/H blocks (B1 to B10) of a data group, will be provided tothe block processor 302. When the SCCC block mode value is equal to‘00’, then the primary RS frame portion will be split into 10 SCCCBlocks according to Table 9. Alternatively, when the SCCC block modevalue is equal to ‘01’, then the primary RS frame will be split into 5SCCC blocks according to Table 10.

When the RS frame mode value is equal to ‘01’, then the block processor302 may receive two RS frame portions. The RS frame mode value of ‘01’will not be used with the SCCC block mode value of ‘01’. The firstportion from the primary RS frame will be SCCC-outer-encoded as SCCCBlocks SCB3, SCB4, SCB5, SCB6, SCB7, and SCB8 by the block processor302. The SCCC Blocks SCB3 and SCB8 will be mapped to region B and theSCCC blocks SCB4, SCB5, SCB6, and SCB7 shall be mapped to region A bythe group formatter 303. The second portion from the secondary RS framewill also be SCCC-outer-encoded, as SCB1, SCB2, SCB9, and SCB10, by theblock processor 302. The group formatter 303 will map the SCCC blocksSCB1 and SCB10 to region D as the M/H blocks B1 and B10, respectively.Similarly, the SCCC blocks SCB2 and SCB9 will be mapped to region C asthe M/H blocks B2 and B9.

The byte-bit converter 512 identifies the mobile service data bytes ofeach SCCC block outputted from the RS frame portion-SCCC block converter511 as data bits, which are then outputted to the convolution encoder513. The convolution encoder 513 performs one of 1/2-rate encoding and1/4-rate encoding on the inputted mobile service data bits.

FIG. 29 illustrates a detailed block diagram of the convolution encoder513. The convolution encoder 513 includes two delay units 521 and 523and three adders 522, 524, and 525. Herein, the convolution encoder 513encodes an input data bit U and outputs the coded bit U to 5 bits (u0 tou4). At this point, the input data bit U is directly outputted asuppermost bit u0 and simultaneously encoded as lower bit u1u2u3u4 andthen outputted. More specifically, the input data bit U is directlyoutputted as the uppermost bit u0 and simultaneously outputted to thefirst and third adders 522 and 525.

The first adder 522 adds the input data bit U and the output bit of thefirst delay unit 521 and, then, outputs the added bit to the seconddelay unit 523. Then, the data bit delayed by a pre-determined time(e.g., by 1 clock) in the second delay unit 523 is outputted as a lowerbit u1 and simultaneously fed-back to the first delay unit 521. Thefirst delay unit 521 delays the data bit fed-back from the second delayunit 523 by a pre-determined time (e.g., by 1 clock). Then, the firstdelay unit 521 outputs the delayed data bit as a lower bit u2 and, atthe same time, outputs the fed-back data to the first adder 522 and thesecond adder 524. The second adder 524 adds the data bits outputted fromthe first and second delay units 521 and 523 and outputs the added databits as a lower bit u3. The third adder 525 adds the input data bit Uand the output of the second delay unit 523 and outputs the added databit as a lower bit u4.

At this point, the first and second delay units 521 and 523 are reset to‘0’, at the starting point of each SCCC block. The convolution encoder513 of FIG. 29 may be used as a 1/2-rate encoder or a 1/4-rate encoder.More specifically, when a portion of the output bit of the convolutionencoder 513, shown in FIG. 29, is selected and outputted, theconvolution encoder 513 may be used as one of a 1/2-rate encoder and a1/4-rate encoder. Table 11 below shown an example of output symbols ofthe convolution encoder 513.

TABLE 11 ¼ rate SCCC block ½ SCCC block mode = mode = Region rate ‘00’‘01’ A, B (u0, u1) (u0, u2), (u1, u3) (u0, u2), C, D (u0, u1), (u3, u4)(u1, u4)

For example, at the 1/2-coding rate, 1 output symbol (i.e., u0 and u1bits) may be selected and outputted. And, at the 1/4-coding rate,depending upon the SCCC block mode, 2 output symbols (i.e., 4 bits) maybe selected and outputted. For example, when the SCCC block mode valueis equal to ‘01’, and when an output symbol configured of u0 and u2 andanother output symbol configured of u1 and u4 are selected andoutputted, a 1/4-rate coding result may be obtained.

The mobile service data encoded at the coding rate of 1/2 or 1/4 by theconvolution encoder 513 are outputted to the symbol interleaver 514. Thesymbol interleaver 514 performs block interleaving, in symbol units, onthe output data symbol of the convolution encoder 513. Morespecifically, the symbol interleaver 514 is a type of block interleaver.Any interleaver performing structural rearrangement (or realignment) maybe applied as the symbol interleaver 514 of the block processor.However, in the present invention, a variable length symbol interleaverthat can be applied even when a plurality of lengths is provided for thesymbol, so that its order may be rearranged, may also be used.

FIG. 30 illustrates a symbol interleaver according to an embodiment ofthe present invention. Particularly, FIG. 30 illustrates an example ofthe symbol interleaver when B=2112 and L=4096. Herein, B indicates ablock length in symbols that are outputted for symbol interleaving fromthe convolution encoder 513. And, L represents a block length in symbolsthat are actually interleaved by the symbol interleaver 514. At thispoint, the block length in symbols B inputted to the symbol interleaver514 is equivalent to 4×SOBL. More specifically, since one symbol isconfigured of 2 bits, the value of B may be set to be equal to 4×SOBL.

In the present invention, when performing the symbol-intereleavingprocess, the conditions of L=2^(m) (wherein m is an integer) and of L≧Bshould be satisfied. If there is a difference in value between B and L,(L−B) number of null (or dummy) symbols is added, thereby generating aninterleaving pattern, as shown in P′(i) of FIG. 30. Therefore, B becomesa block size of the actual symbols that are inputted to the symbolinterleaver 514 in order to be interleaved. L becomes an interleavingunit when the interleaving process is performed by an interleavingpattern generated from the symbol interleaver 514.

Equation 6 shown below describes the process of sequentially receiving Bnumber of symbols, the order of which is to be rearranged, and obtainingan L value satisfying the conditions of L=2^(m) (wherein m is aninteger) and of L≧B, thereby generating the interleaving so as torealign (or rearrange) the symbol order.

In relation to all places, wherein 0≦i≦B−1,P′(i)={89×i×(i+1)/2}mod L   Equation 6

Herein, L≧B, L=2^(m), wherein m is an integer.

As shown in P′(i) of FIG. 30, the order of B number of input symbols and(L−B) number of null symbols is rearranged by using the above-mentionedEquation 6. Then, as shown in P(i) of FIG. 30, the null byte places areremoved, so as to rearrange the order. Starting with the lowest value ofi, the P(i) are shifted to the left in order to fill the empty entrylocations. Thereafter, the symbols of the aligned interleaving patternP(i) are outputted to the symbol-byte converter 515 in order. Herein,the symbol-byte converter 515 converts to bytes the mobile service datasymbols, having the rearranging of the symbol order completed and thenoutputted in accordance with the rearranged order, and thereafteroutputs the converted bytes to the SCCC block-M/H block converter 516.The SCCC block-M/H block converter 516 converts the symbol-interleavedSCCC blocks to M/H blocks, which are then outputted to the groupformatter 303.

If the SCCC block mode value is equal to ‘00’, the SCCC block is mappedat a one-to-one (1:1) correspondence with each M/H block within the datagroup. In another example, if the SCCC block mode value is equal to‘01’, each SCCC block is mapped with two M/H blocks within the datagroup. For example, the SCCC block SCB1 is mapped with (B1, B6), theSCCC block SCB2 is mapped with (B2, B7), the SCCC block SCB3 is mappedwith (B3, B8), the SCCC block SCB4 is mapped with (B4, B9), and the SCCCblock SCB5 is mapped with (B5, B10). The M/H block that is outputtedfrom the SCCC block-M/H block converter 516 is configured of mobileservice data and FEC redundancy. In the present invention, the mobileservice data as well as the FEC redundancy of the M/H block will becollectively considered as mobile service data.

Group Formatter

The group formatter 303 inserts data of M/H blocks outputted from theblock processor 302 to the corresponding M/H blocks within the datagroup, which is formed in accordance with a pre-defined rule. Also, inassociation with the data-deinterleaving process, the group formatter303 inserts various place holders (or known data place holders) in thecorresponding region within the data group. More specifically, apartfrom the encoded mobile service data outputted from the block processor302, the group formatter 303 also inserts MPEG header place holders,non-systematic RS parity place holders, main service data place holders,which are associated with the data deinterleaving in a later process, asshown in FIG. 5.

Herein, the main service data place holders are inserted because themobile service data bytes and the main service data bytes arealternately mixed with one another in regions B to D based upon theinput of the data deinterleaver, as shown in FIG. 5. For example, basedupon the data outputted after data deinterleaving, the place holder forthe MPEG header may be allocated at the very beginning of each packet.Also, in order to configure an intended group format, dummy bytes mayalso be inserted. Furthermore, the group formatter 303 insertsinitialization data (i.e., trellis initialization byte) of the trellisencoding module 256 in the corresponding regions. For example, theinitialization data may be inserted in the beginning of the known datasequence. The initialization data is used for initializing memorieswithin the trellis encoding module 256, and is not transmitted to thereceiving system.

Additionally, the group formatter 303 may also insert signalinginformation, which are encoded and outputted from the signaling encoder304, in corresponding regions within the data group. At this point,reference may be made to the signaling information when the groupformatter 303 inserts each data type and respective place holders in thedata group. The process of encoding the signaling information andinserting the encoded signaling information to the data group will bedescribed in detail in a later process.

After inserting each data type and respective place holders in the datagroup, the group formatter 303 may deinterleave the data and respectiveplace holders, which have been inserted in the data group, as an inverseprocess of the data interleaver, thereby outputting the deinterleaveddata and respective place holders to the packet formatter 305. The groupformatter 303 may include a group format organizer 527, and a datadeinterleaver 529, as shown in FIG. 31. The group format organizer 527inserts data and respective place holders in the corresponding regionswithin the data group, as described above. And, the data deinterleaver529 deinterleaves the inserted data and respective place holders as aninverse process of the data interleaver.

The packet formatter 305 removes the main service data place holders andthe RS parity place holders that were allocated for the deinterleavingprocess from the deinterleaved data being inputted. Then, the packetformatter 305 groups the remaining portion and inserts the 3-byte MPEGheader place holder in an MPEG header having a null packet PID (or anunused PID from the main service data packet). Furthermore, the packetformatter 305 adds a synchronization data byte at the beginning of each187-byte data packet. Also, when the group formatter 303 inserts knowndata place holders, the packet formatter 303 may insert actual knowndata in the known data place holders, or may directly output the knowndata place holders without any modification in order to make replacementinsertion in a later process. Thereafter, the packet formatter 305identifies the data within the packet-formatted data group, as describedabove, as a 188-byte unit mobile service data packet (i.e., MPEG TSpacket), which is then provided to the packet multiplexer 240.

Based upon the control of the controller 201, the packet multiplexer 240multiplexes the data group packet-formatted and outputted from thepacket formatter 306 and the main service data packet outputted from thepacket jitter mitigator 220. Then, the packet multiplexer 240 outputsthe multiplexed data packets to the data randomizer 251 of thepost-processor 250. More specifically, the controller 201 controls thetime-multiplexing of the packet multiplexer 240. If the packetmultiplexer 240 receives 118 mobile service data packets from the packetformatter 305, 37 mobile service data packets are placed before a placefor inserting VSB field synchronization. Then, the remaining 81 mobileservice data packets are placed after the place for inserting VSB fieldsynchronization. The multiplexing method may be adjusted by diversevariables of the system design. The multiplexing method and multiplexingrule of the packet multiplexer 240 will be described in more detail in alater process.

Also, since a data group including mobile service data in-between thedata bytes of the main service data is multiplexed (or allocated) duringthe packet multiplexing process, the shifting of the chronologicalposition (or place) of the main service data packet becomes relative.Also, a system object decoder (i.e., MPEG decoder) for processing themain service data of the receiving system, receives and decodes only themain service data and recognizes the mobile service data packet as anull data packet.

Therefore, when the system object decoder of the receiving systemreceives a main service data packet that is multiplexed with the datagroup, a packet jitter occurs.

At this point, since a multiple-level buffer for the video data existsin the system object decoder and the size of the buffer is relativelylarge, the packet jitter generated from the packet multiplexer 240 doesnot cause any serious problem in case of the video data. However, sincethe size of the buffer for the audio data in the object decoder isrelatively small, the packet jitter may cause considerable problem. Morespecifically, due to the packet jitter, an overflow or underflow mayoccur in the buffer for the main service data of the receiving system(e.g., the buffer for the audio data). Therefore, the packet jittermitigator 220 re-adjusts the relative position of the main service datapacket so that the overflow or underflow does not occur in the systemobject decoder.

In the present invention, examples of repositioning places for the audiodata packets within the main service data in order to minimize theinfluence on the operations of the audio buffer will be described indetail. The packet jitter mitigator 220 repositions the audio datapackets in the main service data section so that the audio data packetsof the main service data can be as equally and uniformly aligned andpositioned as possible. Additionally, when the positions of the mainservice data packets are relatively re-adjusted, associated programclock reference (PCR) values may also be modified accordingly. The PCRvalue corresponds to a time reference value for synchronizing the timeof the MPEG decoder. Herein, the PCR value is inserted in a specificregion of a TS packet and then transmitted.

In the example of the present invention, the packet jitter mitigator 220also performs the operation of modifying the PCR value. The output ofthe packet jitter mitigator 220 is inputted to the packet multiplexer240. As described above, the packet multiplexer 240 multiplexes the mainservice data packet outputted from the packet jitter mitigator 220 withthe mobile service data packet outputted from the pre-processor 230 intoa burst structure in accordance with a pre-determined multiplexing rule.Then, the packet multiplexer 240 outputs the multiplexed data packets tothe data randomizer 251 of the post-processor 250.

If the inputted data correspond to the main service data packet, thedata randomizer 251 performs the same randomizing process as that of theconventional randomizer. More specifically, the synchronization bytewithin the main service data packet is deleted. Then, the remaining 187data bytes are randomized by using a pseudo random byte generated fromthe data randomizer 251. Thereafter, the randomized data are outputtedto the RS encoder/non-systematic RS encoder 252.

On the other hand, if the inputted data correspond to the mobile servicedata packet, the data randomizer 251 may randomize only a portion of thedata packet. For example, if it is assumed that a randomizing processhas already been performed in advance on the mobile service data packetby the pre-processor 230, the data randomizer 251 deletes thesynchronization byte from the 4-byte MPEG header included in the mobileservice data packet and, then, performs the randomizing process only onthe remaining 3 data bytes of the MPEG header. Thereafter, therandomized data bytes are outputted to the RS encoder/non-systematic RSencoder 252. More specifically, the randomizing process is not performedon the remaining portion of the mobile service data excluding the MPEGheader. In other words, the remaining portion of the mobile service datapacket is directly outputted to the RS encoder/non-systematic RS encoder252 without being randomized. Also, the data randomizer 251 may or maynot perform a randomizing process on the known data (or known data placeholders) and the initialization data included in the mobile service datapacket.

The RS encoder/non-systematic RS encoder 252 performs an RS encodingprocess on the data being randomized by the data randomizer 251 or onthe data bypassing the data randomizer 251, so as to add 20 bytes of RSparity data. Thereafter, the processed data are outputted to the datainterleaver 253. Herein, if the inputted data correspond to the mainservice data packet, the RS encoder/non-systematic RS encoder 252performs the same systematic RS encoding process as that of theconventional broadcasting system, thereby adding the 20-byte RS paritydata at the end of the 187-byte data. Alternatively, if the inputteddata correspond to the mobile service data packet, the RSencoder/non-systematic RS encoder 252 performs a non-systematic RSencoding process. At this point, the 20-byte RS parity data obtainedfrom the non-systematic RS encoding process are inserted in apre-decided parity byte place within the mobile service data packet.

The data interleaver 253 corresponds to a byte unit convolutionalinterleaver. The output of the data interleaver 253 is inputted to theparity replacer 254 and to the non-systematic RS encoder 255.

Meanwhile, a process of initializing a memory within the trellisencoding module 256 is primarily required in order to decide the outputdata of the trellis encoding module 256, which is located after theparity replacer 254, as the known data pre-defined according to anagreement between the receiving system and the transmitting system. Morespecifically, the memory of the trellis encoding module 256 should firstbe initialized before the received known data sequence istrellis-encoded.

At this point, the beginning portion of the known data sequence that isreceived corresponds to the initialization data and not to the actualknown data. Herein, the initialization data has been included in thedata by the group formatter within the pre-processor 230 in an earlierprocess. Therefore, the process of replacing the initialization datawith memory values within the trellis encoding module 256 are requiredto be performed immediately before the inputted known data sequence istrellis-encoded.

More specifically, the initialization data are replaced with the memoryvalue within the trellis encoding module 256, thereby being inputted tothe trellis encoding module 256. At this point, the memory valuereplacing the initialization data are process with (or calculated by) anexclusive OR (XOR) operation with the respective memory value within thetrellis encoding module 256, so as to be inputted to the correspondingmemory. Therefore, the corresponding memory is initialized to ‘0’.Additionally, a process of using the memory value replacing theinitialization data to re-calculate the RS parity, so that there-calculated RS parity value can replace the RS parity being outputtedfrom the data interleaver 253, is also required.

Therefore, the non-systematic RS encoder 255 receives the mobile servicedata packet including the initialization data from the data interleaver253 and also receives the memory value from the trellis encoding module256.

Among the inputted mobile service data packet, the initialization dataare replaced with the memory value, and the RS parity data that areadded to the mobile service data packet are removed and processed withnon-systematic RS encoding. Thereafter, the new RS parity obtained byperforming the non-systematic RS encoding process is outputted to theparity replacer 255. Accordingly, the parity replacer 255 selects theoutput of the data interleaver 253 as the data within the mobile servicedata packet, and the parity replacer 255 selects the output of thenon-systematic RS encoder 255 as the RS parity. The selected data arethen outputted to the trellis encoding module 256.

Meanwhile, if the main service data packet is inputted or if the mobileservice data packet, which does not include any initialization data thatare to be replaced, is inputted, the parity replacer 254 selects thedata and RS parity that are outputted from the data interleaver 253.Then, the parity replacer 254 directly outputs the selected data to thetrellis encoding module 256 without any modification. The trellisencoding module 256 converts the byte-unit data to symbol units andperforms a 12-way interleaving process so as to trellis-encode thereceived data. Thereafter, the processed data are outputted to thesynchronization multiplexer 260.

FIG. 32 illustrates a detailed diagram of one of 12 trellis encodersincluded in the trellis encoding module 256. Herein, the trellis encoderincludes first and second multiplexers 531 and 541, first and secondexclusive OR (XOR) gates 532 and 542, and first to third memories 533,542, and 544.

More specifically, the first to third memories 533, 542, and 544 areinitialized by the memory value instead of the initialization data fromthe parity replacer 254. More specifically, when the first symbol (i.e.,two bits), which are converted from initialization data (i.e., eachtrellis initialization data byte), are inputted, the input bits of thetrellis encoder will be replaced by the memory values of the trellisencoder, as shown in FIG. 32.

Since 2 symbols (i.e., 4 bits) are required for trellis initialization,the last 2 symbols (i.e., 4 bits) from the trellis initialization bytesare not used for trellis initialization and are considered as a symbolfrom a known data byte and processed accordingly.

When the trellis encoder is in the initialization mode, the input comesfrom an internal trellis status (or state) and not from the parityreplacer 254. When the trellis encoder is in the normal mode, the inputsymbol (X2X1) provided from the parity replacer 254 will be processed.The trellis encoder provides the converted (or modified) input data fortrellis initialization to the non-systematic RS encoder 255.

More specifically, when a selection signal designates a normal mode, thefirst multiplexer 531 selects an upper bit X2 of the input symbol. And,when a selection signal designates an initialization mode, the firstmultiplexer 531 selects the output of the first memory 533 and outputsthe selected output data to the first XOR gate 532. The first XOR gate532 performs XOR operation on the output of the first multiplexer 531and the output of the first memory 533, thereby outputting the addedresult to the first memory 533 and, at the same time, as a mostsignificant (or uppermost) bit Z2. The first memory 533 delays theoutput data of the first XOR gate 532 by 1 clock, thereby outputting thedelayed data to the first multiplexer 531 and the first XOR gate 532.

Meanwhile, when a selection signal designates a normal mode, the secondmultiplexer 541 selects a lower bit X1 of the input symbol. And, when aselection signal designates an initialization mode, the secondmultiplexer 541 selects the output of the second memory 542, therebyoutputting the selected result to the second XOR gate 543 and, at thesame time, as a lower bit Z1. The second XOR gate 543 performs XORoperation on the output of the second multiplexer 541 and the output ofthe second memory 542, thereby outputting the added result to the thirdmemory 544. The third memory 544 delays the output data of the secondXOR gate 543 by 1 clock, thereby outputting the delayed data to thesecond memory 542 and, at the same time, as a least significant (orlowermost) bit Z0. The second memory 542 delays the output data of thethird memory 544 by 1 clock, thereby outputting the delayed data to thesecond XOR gate 543 and the second multiplexer 541.

The select signal designates an initialization mode during the first twosymbols that are converted from the initialization data.

For example, when the select signal designates an initialization mode,the first XOR gate 532 performs an XOR operation on the value of thefirst memory 533, which is provided through the first multiplexer 531,and on a memory value that is directly provided from the first memory533. That is, the first XOR gate 532 performs an XOR operation on 2 bitshaving the same value. Generally, when only one of the two bitsbelonging to the operand is ‘1’, the result of the XOR gate is equal to‘1’. Otherwise, the result of the XOR gate becomes equal to ‘0’.Therefore, when the value of the first memory 533 is processed with anXOR operation, the result is always equal to ‘0’. Furthermore, since theoutput of the first XOR gate 532, i.e., ‘0’, is inputted to the firstmemory 533, the first memory 533 is initialized to ‘0’.

Similarly, when the select signal designates an initialization mode, thesecond XOR gate 543 performs an XOR operation on the value of the secondmemory 542, which is provided through the second multiplexer 541, and ona memory value that is directly provided from the second memory 542.Therefore, the output of the second XOR gate 543 is also always equal to‘0’. Since the output of the second XOR gate 543, i.e., ‘0’, is inputtedto the third memory 544, the third memory 544 is also initialized to‘0’. The output of the third memory 544 is inputted to the second memory542 in the next clock, thereby initializing the second memory 542 to‘0’. In this case also, the select signal designates the initializationmode.

More specifically, when the first symbol being converted from theinitialization data byte replaces the values of the first memory 533 andthe second memory 542, thereby being inputted to the trellis encoder,each of the first and third memories 533 and 544 within the trellisencoder is initialized to ‘00’. Following the process, when the secondsymbol being converted from the initialization data byte replaces thevalues of the first memory 533 and the second memory 542, thereby beinginputted to the trellis encoder, each of the first, second, and thirdmemories 533, 542, and 544 within the trellis encoder is initialized to‘000’.

As described above, 2 symbols are required to initialize the memory ofthe trellis encoder. At this point, while the select signal designatesan initialization mode, the output bits (X2′X1′) of the first and secondmemories 533 and 542 are inputted to the non-systematic RS encoder 255,so as to perform a new RS parity calculation process.

The synchronization multiplexer 260 inserts a field synchronizationsignal and a segment synchronization signal to the data outputted fromthe trellis encoding module 256 and, then, outputs the processed data tothe pilot inserter 271 of the transmission unit 270. Herein, the datahaving a pilot inserted therein by the pilot inserter 271 are modulatedby the modulator 272 in accordance with a pre-determined modulatingmethod (e.g., a VSB method). Thereafter, the modulated data aretransmitted to each receiving system though the radio frequency (RF)up-converter 273.

Multiplexing Method of Packet Multiplexer

Data of the error correction encoded and 1/H-rate encoded primary RSframe (i.e., when the RS frame mode value is equal to ‘00’) orprimary/secondary RS frame (i.e., when the RS frame mode value is equalto ‘01’), are divided into a plurality of data groups by the groupformatter 303. Then, the divided data portions are assigned to at leastone of regions A to D of each data group or to an M/H block among theM/H blocks B1 to B10, thereby being deinterleaved. Then, thedeinterleaved data group passes through the packet formatter 305,thereby being multiplexed with the main service data by the packetmultiplexer 240 based upon a de-decided multiplexing rule. The packetmultiplexer 240 multiplexes a plurality of consecutive data groups, sothat the data groups are assigned to be spaced as far apart from oneanother as possible within the sub-frame. For example, when it isassumed that 3 data groups are assigned to a sub-frame, the data groupsare assigned to a 1^(st) slot (Slot #0), a 5^(th) slot (Slot #4), and a9^(th) slot (Slot #8) in the sub-frame, respectively.

As described-above, in the assignment of the plurality of consecutivedata groups, a plurality of parades are multiplexed and outputted so asto be spaced as far apart from one another as possible within asub-frame. For example, the method of assigning data groups and themethod of assigning parades may be identically applied to all sub-framesfor each M/H frame or differently applied to each M/H frame.

FIG. 10 illustrates an example of a plurality of data groups included ina single parade, wherein the number of data groups included in asub-frame is equal to ‘3’, and wherein the data groups are assigned toan M/H frame by the packet multiplexer 240. Referring to FIG. 10, 3 datagroups are sequentially assigned to a sub-frame at a cycle period of 4slots. Accordingly, when this process is equally performed in the 5sub-frames included in the corresponding M/H frame, 15 data groups areassigned to a single M/H frame. Herein, the 15 data groups correspond todata groups included in a parade.

When data groups of a parade are assigned as shown in FIG. 10, thepacket multiplexer 240 may either assign main service data to each datagroup, or assign data groups corresponding to different parades betweeneach data group. More specifically, the packet multiplexer 240 mayassign data groups corresponding to multiple parades to one M/H frame.Basically, the method of assigning data groups corresponding to multipleparades is very similar to the method of assigning data groupscorresponding to a single parade. In other words, the packet multiplexer240 may assign data groups included in other parades to an M/H frameaccording to a cycle period of 4 slots. At this point, data groups of adifferent parade may be sequentially assigned to the respective slots ina circular method. Herein, the data groups are assigned to slotsstarting from the ones to which data groups of the previous parade havenot yet been assigned. For example, when it is assumed that data groupscorresponding to a parade are assigned as shown in FIG. 10, data groupscorresponding to the next parade may be assigned to a sub-frame startingeither from the 12^(th) slot of a sub-frame.

FIG. 11 illustrates an example of assigning and transmitting 3 parades(Parade #0, Parade #1, and Parade #2) to an M/H frame. For example, whenthe 1^(st) parade (Parade #0) includes 3 data groups for each sub-frame,the packet multiplexer 240 may obtain the positions of each data groupswithin the sub-frames by substituting values ‘0’ to ‘2’ for i inEquation 1. More specifically, the data groups of the 1^(st) parade(Parade #0) are sequentially assigned to the 1^(st), 5^(th), and 9^(th)slots (Slot #0, Slot #4, and Slot #8) within the sub-frame. Also, whenthe 2^(nd) parade includes 2 data groups for each sub-frame, the packetmultiplexer 240 may obtain the positions of each data groups within thesub-frames by substituting values ‘3’ and ‘4’ for i in Equation 1. Morespecifically, the data groups of the 2^(nd) parade (Parade #1) aresequentially assigned to the 2^(nd) and 12^(th) slots (Slot #3 and Slot#11) within the sub-frame. Finally, when the 3^(rd) parade includes 2data groups for each sub-frame, the packet multiplexer 240 may obtainthe positions of each data groups within the sub-frames by substitutingvalues ‘5’ and ‘6’ for i in Equation 1. More specifically, the datagroups of the 3^(rd) parade (Parade #2) are sequentially assigned andoutputted to the 7^(th) and 11^(th) slots (Slot #6 and Slot #10) withinthe sub-frame.

As described above, the packet multiplexer 240 may multiplex and outputdata groups of multiple parades to a single M/H frame, and, in eachsub-frame, the multiplexing process of the data groups may be performedserially with a group space of 4 slots from left to right. Therefore, anumber of groups of one parade per sub-frame (NOG) may correspond to anyone integer from ‘1’ to ‘8’. Herein, since one M/H frame includes 5sub-frames, the total number of data groups within a parade that can beallocated to an M/H frame may correspond to any one multiple of ‘5’ranging from ‘5’ to ‘40’.

Processing Signaling Information

The present invention assigns signaling information areas for insertingsignaling information to some areas within each data group. FIG. 33illustrates an example of assigning signaling information areas forinserting signaling information starting from the 1^(st) segment of the4^(th) M/H block (B4) to a portion of the 2^(nd) segment. Morespecifically, 276(=207+69) bytes of the 4^(th) M/H block (B4) in eachdata group are assigned as the signaling information area. In otherwords, the signaling information area consists of 207 bytes of the1^(st) segment and the first 69 bytes of the 2^(nd) segment of the4^(th) M/H block (B4). For example, the 1^(st) segment of the 4^(th) M/Hblock (B4) corresponds to the 17^(th) or 173^(rd) segment of a VSBfield.

The signaling information that is to be inserted in the signalinginformation area is FEC-encoded by the signaling encoder 304, therebyinputted to the group formatter 303. The signaling information mayinclude a transmission parameter which is included in the payload regionof an OM packet, and then received to the demultiplexer 210.

The group formatter 303 inserts the signaling information, which isFEC-encoded and outputted by the signaling encoder 304, in the signalinginformation area within the data group. Herein, the signalinginformation may be identified by two different types of signalingchannels: a transmission parameter channel (TPC) and a fast informationchannel (FIC).

Herein, the TPC data corresponds to signaling information includingtransmission parameters, such as RS frame information, RS encodinginformation, FIC information, data group information, SCCC information,and M/H frame information and so on. However, the TPC data presentedherein is merely exemplary. And, since the adding or deleting ofsignaling information included in the TPC may be easily adjusted andmodified by one skilled in the art, the present invention will,therefore, not be limited to the examples set forth herein.

Furthermore, the FIC data is provided to enable a fast serviceacquisition of data receivers, and the FIC data includes cross layerinformation between the physical layer and the upper layer(s).

FIG. 34 illustrates a detailed block diagram of the signaling encoder304 according to the present invention. Referring to FIG. 34, thesignaling encoder 304 includes a TPC encoder 561, an FIC encoder 562, ablock interleaver 563, a multiplexer 564, a signaling randomizer 565,and an iterative turbo encoder 566.

The TPC encoder 561 receives 10-bytes of TPC data and performs(18,10)-RS encoding on the 10-bytes of TPC data, thereby adding 8 bytesof parity data to the 10 bytes of TPC data. The 18 bytes of RS-encodedTPC data are outputted to the multiplexer 564.

The FIC encoder 562 receives 37-bytes of FIC data and performs(51,37)-RS encoding on the 37-bytes of FIC data, thereby adding 14 bytesof parity data to the 37 bytes of FIC data. Thereafter, the 51 bytes ofRS-encoded FIC data are inputted to the block interleaver 563, therebybeing interleaved in predetermined block units. Herein, the blockinterleaver 563 corresponds to a variable length block interleaver. Theblock interleaver 563 interleaves the FIC data within each sub-frame inTNoG(column)×51(row) block units and then outputs the interleaved datato the multiplexer 564. Herein, the TNoG corresponds to the total numberof data groups being assigned to a sub-frame. The block interleaver 563is synchronized with the first set of FIC data in each sub-frame.

The block interleaver 563 writes 51 bytes of incoming (or inputted) RScodewords in a row direction (i.e., row-by-row) and left-to-right andup-to-down directions and reads 51 bytes of RS codewords in a columndirection (i.e., column-by-column) and left-to-right and up-to-downdirections, thereby outputting the RS codewords.

The multiplexer 564 multiplexes the RS-encoded TPC data from the TPCencoder 561 and the block-interleaved FIC data from the blockinterleaver 563 along a time axis. Then, the multiplexer 564 outputs 69bytes of the multiplexed data to the signaling randomizer 565. Thesignaling randomizer 565 randomizes the multiplexed data and outputs therandomized data to the iterative turbo encoder 566. The signalingrandomizer 565 may use the same generator polynomial of the randomizerused for mobile service data. Also, initialization occurs in each datagroup.

The iterative turbo encoder 566 corresponds to an inner encoderperforming iterative turbo encoding in a PCCC method on the randomizeddata (i.e., signaling information data). The iterative turbo encoder 566may include 6 even component encoders and 6 odd component encoders.

FIG. 35 illustrates an example of a syntax structure of TPC data beinginputted to the TPC encoder 561. The TPC data are inserted in thesignaling information area of each data group and then transmitted. TheTPC data may include a sub-frame number field, a slot_number field, aparade_id field, a starting_group_number (SGN) field, a number_of_groups(NoG) field, a parade_repetition_cycle (PRC) field, an RS_frame_modefield, an RS_code_mode primary field, an RS_code_mode secondary field,an SCCC_block_mode field, an SCCC_outer_code_mode_A field, anSCCC_outer_code_mode_B field, an SCCC_outer_code_mode_C field, anSCCC_outer_code_mode_D field, an FIC_version field, aparade_continuity_counter field, and a TNoG field.

The Sub-Frame_number field corresponds to the current Sub-Frame numberwithin the M/H frame, which is transmitted for M/H framesynchronization. The value of the Sub-Frame_number field may range from0 to 4. The Slot_number field indicates the current slot number withinthe sub-frame, which is transmitted for M/H frame synchronization. Also,the value of the Sub-Frame_number field may range from 0 to 15. TheParade_id field identifies the parade to which this group belongs. Thevalue of this field may be any 7-bit value. Each parade in a M/Htransmission shall have a unique Parade_id field.

Communication of the Parade_id between the physical layer and themanagement layer may be performed by means of an Ensemble_id fieldformed by adding one bit to the left of the Parade_id field. If theEnsemble_id field is used for the primary Ensemble delivered throughthis parade, the added MSB shall be equal to ‘0’. Otherwise, if theEnsemble_id field is used for the secondary ensemble, the added MSBshall be equal to ‘1’. Assignment of the Parade_id field values mayoccur at a convenient level of the system, usually in the managementlayer. The starting_group_number (SGN) field shall be the firstSlot_number for a parade to which this group belongs, as determined byEquation 1 (i.e., after the Slot numbers for all preceding parades havebeen calculated). The SGN and NoG shall be used according to Equation 1to obtain the slot numbers to be allocated to a parade within thesub-frame.

The number_of_Groups (NoG) field shall be the number of groups in asub-frame assigned to the parade to which this group belongs, minus 1,e.g., NoG=0 implies that one group is allocated (or assigned) to thisparade in a sub-frame. The value of NoG may range from 0 to 7. Thislimits the amount of data that a parade may take from the main (legacy)service data, and consequently the maximum data that can be carried byone parade. The slot numbers assigned to the corresponding Parade can becalculated from SGN and NoG, using Equation 1. By taking each parade insequence, the specific slots for each parade will be determined, andconsequently the SGN for each succeeding parade. For example, if for aspecific parade SGN=3 and NoG=3 (010b for 3-bit field of NoG),substituting i=3, 4, and 5 in Equation 1 provides slot numbers 12, 2,and 6.

The Parade repetition cycle (PRC) field corresponds to the cycle timeover which the parade is transmitted, minus 1, specified in units of M/Hframes, as described in Table 12.

TABLE 12 PRC Description 000 This parade shall be transmitted once everyM/H frame. 001 This parade shall be transmitted once every 2 M/H frames.010 This parade shall be transmitted once every 3 M/H frames. 011 Thisparade shall be transmitted once every 4 M/H frames. 100 This paradeshall be transmitted once every 5 M/H frames. 101 This parade shall betransmitted once every 6 M/H frames. 110 This parade shall betransmitted once every 7 M/H frames. 111 Reserved

For example, if PRC field value is equal to ‘001’, this indicates thatthe parade shall be transmitted once every 2 M/H frame.

The RS_Frame_mode field shall be as defined in Table 1. TheRS_Frame_mode field represents that one parade transmits one RS frame ortwo RS frames.

The RS_code_mode_primary field shall be the RS code mode for the primaryRS frame. Herein, the RS_code_mode_primary field is defined in Table 6.

The RS_code_mode_secondary field shall be the RS code mode for thesecondary RS frame. Herein, the RS_code_mode_secondary field is definedin Table 6.

The SCCC_Block_mode field represents how M/H blocks within a data groupare assigned to SCCC block. The SCCC_Block_mode field shall be asdefined in Table 7.

The SCCC_outer_code_mode_A field corresponds to the SCCC outer code modefor Region A within a data group. The SCCC outer code mode is defined inTable 8.

The SCCC_outer_code_mode_B field corresponds to the SCCC outer code modefor Region B within the data group. The SCCC_outer_code_mode_C fieldcorresponds be the SCCC outer code mode for Region C within the datagroup. And, the SCCC_outer_code_mode_D field corresponds to the SCCCouter code mode for Region D within the data group.

The FIC_version field represents a version of FIC data.

The Parade_continuity_counter field counter may increase from 0 to 15and then repeat its cycle. This counter shall increment by 1 every(PRC+1) M/H frames. For example, as shown in Table 12, PRC=011 (decimal3) implies that Parade_continuity_counter increases every fourth M/Hframe.

The TNoG field may be identical for all sub-frames in an

M/H Frame.

However, the information included in the TPC data presented herein ismerely exemplary. And, since the adding or deleting of informationincluded in the TPC may be easily adjusted and modified by one skilledin the art, the present invention will, therefore, not be limited to theexamples set forth herein.

Since the TPC data (excluding the Sub-Frame_number field and theSlot_number field) for each parade do not change their values during anM/H frame, the same information is repeatedly transmitted through allM/H groups belonging to the corresponding parade during an M/H frame.This allows very robust and reliable reception of the TPC data. Becausethe Sub-Frame_number and the Slot_number are increasing counter values,they also are robust due to the transmission of regularly expectedvalues.

Furthermore, the FIC data is provided to enable a fast serviceacquisition of data receivers, and the FIC information includes crosslayer information between the physical layer and the upper layer(s).

FIG. 36 illustrates an example of a transmission scenario of the TPCdata and the FIC data. The values of the Sub-Frame_number field,Slot_number field, Parade_id field, Parade_repetition_cycle field, andParade_continuity_counter field may corresponds to the current M/H framethroughout the 5 sub-frames within a specific M/H frame. Some of TPCparameters and FIC data are signaled in advance.

The SGN, NoG and all FEC modes may have values corresponding to thecurrent M/H frame in the first two sub-frames. The SGN, NoG and all FECmodes may have values corresponding to the frame in which the paradenext appears throughout the 3^(rd), 4^(th) and 5^(th) sub-frames of thecurrent M/H frame. This enables the M/H receivers to receive (oracquire) the transmission parameters in advance very reliably.

For example, when Parade_repetition_cycle=‘000’, the values of the3^(rd), 4^(th), and 5^(th) sub-frames of the current M/H framecorrespond to the next M/H frame. Also, whenParade_repetition_cycle=‘011’, the values of the 3^(rd), 4^(th), and5^(th) sub-frames of the current M/H frame correspond to the 4^(th) M/Hframe and beyond.

The FIC_version field and the FIC_data field may have values that applyto the current M/H Frame during the 1^(st) sub-frame and the 2^(nd)sub-frame, and they shall have values corresponding to the M/H frameimmediately following the current M/H frame during the 3^(rd), 4^(th),and 5^(th) sub-frames of the current M/H frame.

Meanwhile, the receiving system may turn the power on only during a slotto which the data group of the designated (or desired) parade isassigned, and the receiving system may turn the power off during theremaining slots, thereby reducing power consumption of the receivingsystem. Such characteristic is particularly useful in portable or mobilereceivers, which require low power consumption. For example, it isassumed that data groups of a 1^(st) parade with NOG=3, a 2^(nd) paradewith NOG=2, and a 3^(rd) parade with NOG=3 are assigned to one M/Hframe, as shown in FIG. 37. It is also assumed that the user hasselected a mobile service included in the 1^(st) parade using the keypadprovided on the remote controller or terminal. In this case, thereceiving system turns the power on only during a slot that data groupsof the 1^(st) parade is assigned, as shown in FIG. 37, and turns thepower off during the remaining slots, thereby reducing powerconsumption, as described above. At this point, the power is required tobe turned on briefly earlier than the slot to which the actualdesignated data group is assigned (or allocated). This is to enable thetuner or demodulator to converge in advance.

Assignment of Known Data (or Training Signal)

In addition to the payload data, the M/H transmission system insertslong and regularly spaced training sequences into each group. Theregularity is an especially useful feature since it provides thegreatest possible benefit for a given number of training symbols inhigh-Doppler rate conditions. The length of the training sequences isalso chosen to allow fast acquisition of the channel during burstedpower-saving operation of the demodulator. Each group contains 6training sequences. The training sequences are specified beforetrellis-encoding. The training sequences are then trellis-encoded andthese trellis-encoded sequences also are known sequences. This isbecause the trellis encoder memories are initialized to pre-determinedvalues at the beginning of each sequence. The form of the 6 trainingsequences at the byte level (before trellis-encoding) is shown in FIG.38. This is the arrangement of the training sequence at the groupformatter 303. FIG. 76 illustrates an example of a known data (training)sequence represented using numbers at the byte level according to thepresent invention. In FIG. 76, known data (training) bytes includetrellis initialization bytes.

The 1^(st) training sequence is located at the last 2 segments of the3^(rd) M/H block (B3). The 2^(nd) training sequence may be inserted atthe 2^(nd) and 3^(rd) segments of the 4^(th) M/H block (B4). The 2^(nd)training sequence is next to the signaling area, as shown in FIG. 5.Then, the 3^(rd) training sequence, the 4^(th) training sequence, the5^(th) training sequence, and the 6^(th) training sequence may be placedat the last 2 segments of the 4^(th), 5^(th), 6^(th), and 7^(th) M/Hblocks (B4, B5, B6, and B7), respectively. As shown in FIG. 38, the1^(st) training sequence, the 3^(rd) training sequence, the 4^(th)training sequence, the 5^(th) training sequence, and the 6^(th) trainingsequence are spaced 16 segments apart from one another. Referring toFIG. 38, the dotted area indicates trellis initialization data bytes,the lined area indicates training data bytes, and the white areaincludes other bytes such as the FEC-coded M/H service data bytes,FEC-coded signaling data, main service data bytes, RS parity data bytes(for backwards compatibility with legacy ATSC receivers) and/or dummydata bytes.

FIG. 39 illustrates the training sequences (at the symbol level) aftertrellis-encoding by the trellis encoder.

Referring to FIG. 39, the dotted area indicates data segment syncsymbols, the lined area indicates training data symbols, and the whitearea includes other symbols, such as FEC-coded mobile service datasymbols, FEC-coded signaling data, main service data symbols, RS paritydata symbols (for backwards compatibility with legacy ATSC receivers),dummy data symbols, trellis initialization data symbols, and/or thefirst part of the training sequence data symbols. Due to theintra-segment interleaving of the trellis encoder, various types of datasymbols will be mixed in the white area.

After the trellis-encoding process, the last 1416 (=588+828) symbols ofthe 1^(st) training sequence, the 3^(rd) training sequence, the 4^(th)training sequence, the 5^(th) training sequence, and the 6^(th) trainingsequence commonly share the same data pattern. Including the datasegment synchronization symbols in the middle of and after eachsequence, the total length of each common training pattern is 1424symbols. The 2^(nd) training sequence has a first 528-symbol sequenceand a second 528-symbol sequence that have the same data pattern. Morespecifically, the 528-symbol sequence is repeated after the 4-symboldata segment synchronization signal. At the end of each trainingsequence, the memory contents of the twelve modified trellis encodersshall be set to zero (0).

FIG. 77 illustrates an example of a training sequence represented usingnumbers at the symbol according to the present invention. In FIG. 77, aVSB level value −7 is mapped to number 0, a VSB level value −5 is mappedto number 1, a VSB level value −3 is mapped to number 2, a VSB levelvalue −1 is mapped to number 3, a VSB level value 1 is mapped to number4, a VSB level value 3 is mapped to number 5, a VSB level value 5 ismapped to number 6, and a VSB level value 7 is mapped to number 7.

Receiving System

FIG. 40 is a block diagram illustrating a receiving system according toan embodiment of the present invention.

The receiving system of FIG. 40 includes a tuner 1301, a demodulatingunit 1302, a demultiplexer 1303, a program table buffer 1304, a programtable decoder 1305, a program table storage unit 1306, a data handler1307, a middleware engine 1308, an A/V decoder 1309, an A/Vpost-processor 1310, an application manager 1311, and a user interface1314. The application manager 1311 may include a channel manager 1312and a service manager 1313.

In FIG. 40, solid lines indicate data flows and dotted lines indicatecontrol flows.

The tuner 1301 tunes to a frequency of a specific channel through any ofan antenna, a cable, or a satellite and down-converts the frequency toan Intermediate Frequency (IF) signal and outputs the IF signal to thedemodulating unit 1302. Here, the tuner 1301 is controlled by thechannel manager 1312 in the application manager 1311 and reports theresult and strength of a broadcast signal of the tuned channel to thechannel manager 1312. Data received through the frequency of thespecific channel includes main service data, mobile service data, atransmission parameter, and program table information for decoding themain service data and the mobile service data.

The demodulating unit 1302 performs VSB demodulation, channelequalization, etc., on the signal output from the tuner 1301 andidentifies and separately outputs main service data and mobile servicedata. The demodulating unit 1302 will be described in detail in a later.

On the other hand, the transmitter can transmit signaling information(or TPC information) including transmission parameters by inserting thesignaling information into at least one of a field synchronizationregion, a known data region, and a mobile service data region.Accordingly, the demodulating unit 1302 can extract the transmissionparameters from the field synchronization region, the known data region,and the mobile service data region.

The transmission parameters may include M/H frame information, sub-frameinformation, slot information, parade-related information (for example,a parade_id, a parade repeat period, etc.), information of data groupsin a sub-frame, RS frame mode information, RS code mode information,SCCC block mode information, SCCC outer code mode information, FICversion information, etc.

The demodulating unit 1302 performs block decoding, RS frame decoding,etc., using the extracted transmission parameters. For example, thedemodulating unit 1302 performs block decoding of each region in a datagroup with reference to SCCC-related information (for example, SCCCblock mode information or an SCCC outer code mode) included in thetransmission parameters and performs RS frame decoding of each regionincluded in the data group with reference to RS-related information (forexample, an RS code mode).

In the embodiment of the present invention, an RS frame including mobileservice data demodulated by the demodulating unit 1302 is input to thedemultiplexer 1303.

That is, data inputted to the demultiplexer 1303 has an RS frame dataformat as shown in FIG. 17( a) or FIG. 17( b). More specifically, the RSframe decoder of the demodulating unit 1302 performs the reverse of theencoding process performed at the RS frame encoder of the transmissionsystem to correct errors in the RS frame and then outputs theerror-corrected RS frame to a data derandomizer. The data derandomizerthen performs derandomizing on the error-corrected RS frame through thereverse of the randomizing process performed at the transmission systemto obtain an RS frame as shown in FIG. 17( a) or FIG. 17( b).

The demultiplexer 1303 may receive RS frames of all parades and may alsoreceive only an RS frame of a parade including a mobile service that theuser desires to receive through power supply control. For example, whenRS frames of all parades are received, the demultiplexer 1303 candemultiplex a parade including a mobile service that the user desires toreceive using a parade_id.

One parade carries one or two RS frames and one ensemble is mapped toone RS frame. Therefore, when one parade carries two RS frames, thedemultiplexer 1303 needs to identify an RS frame carrying an ensembleincluding mobile service data to be decoded from a parade containing amobile service that the user desires to receive. That is, when areceived single parade or a parade demultiplexed from a plurality ofparades carries a primary ensemble and a secondary ensemble, thedemultiplexer 1303 selects one of the primary and secondary ensembles.

In an embodiment, the demultiplexer 1303 can demultiplex an RS framecarrying an ensemble including mobile service data to be decoded usingan ensemble_id created by adding one bit to a left position of theparade_id.

The demultiplexer 1303 refers to the M/H header of the M/H service datapacket within the RS frame corresponding to the ensemble including themobile service data that are to be decoded, thereby identifying when thecorresponding M/H service data packet is the program table informationor the IP datagram of the mobile service data. Alternatively, when theprogram table information and the mobile service data are bothconfigured in the form of IP datagrams, the demultiplexer 1303 may usethe IP address in order to identify the IP datagram of the program tableinformation and the mobile service data.

Herein, the identified program table information is outputted to theprogram table buffer 1304. And, audio/video/data streams are separatedfrom the IP datagram of mobile service data that are to be selectedamong the IP datagrams of the identified mobile service data, therebybeing respectively outputted to the A/V decoder 1309 and/or the datahandler 1307.

According to an embodiment of the present invention, when thestuff_indicator field within the M/H header of the M/H service datapacket indicates that stuffing bytes are inserted in the payload of thecorresponding M/H service data packet, the demultiplexer 1303 removesthe stuffing bytes from the payload of the corresponding M/H servicedata packet. Then, the demultiplexer 1303 identifies the program tableinformation and the mobile service data. Thereafter, the demultiplexer1303 identifies A/V/D streams from the identified mobile service data.

The program table buffer 1304 temporarily stores the section-typeprogram table information and then outputs the section-type programtable information to the program table decoder 1305.

The program table decoder 1305 identifies tables using a table_id and asection_length in the program table information and parses sections ofthe identified tables and produces and stores a database of the parsedresults in the program table storage unit 1306. For example, the programtable decoder 1305 collects sections having the same table identifier(table_id) to construct a table. The program table decoder 1305 thenparses the table and produces and stores a database of the parsedresults in the program table storage unit 1306.

The A/V decoder 1309 decodes the audio and video streams outputted fromthe demultiplexer 1303 using audio and video decoding algorithms,respectively. The decoded audio and video data is outputted to the A/Vpost-processor 1310.

Here, at least one of an AC-3 decoding algorithm, an MPEG 2 audiodecoding algorithm, an MPEG 4 audio decoding algorithm, an AAC decodingalgorithm, an AAC+ decoding algorithm, an HE AAC decoding algorithm, anAAC SBR decoding algorithm, an MPEG surround decoding algorithm, and aBSAC decoding algorithm can be used as the audio decoding algorithm andat least one of an MPEG 2 video decoding algorithm, an MPEG 4 videodecoding algorithm, an H.264 decoding algorithm, an SVC decodingalgorithm, and a VC-1 decoding algorithm can be used as the audiodecoding algorithm.

The data handler 8507 processes data stream packets required for databroadcasting among data stream packets separated (or identified) by thedemultiplexer 1303 and provides the processed data stream packets to themiddleware engine 1310 to allow the middleware engine 1310 to bemultiplexed them with A/V data. In an embodiment, the middleware engine1310 is a Java middleware engine.

The application manager 1311 receives a key input from the TV viewer anddisplays a Graphical User Interface (GUI) on the TV screen in responseto a viewer request through a User Interface (UI). The applicationmanager 1311 also writes and reads information regarding overall GUIcontrol of the TV, user requests, and TV system states to and from amemory (for example, NVRAM or flash memory). In addition, theapplication manager 1311 can receive parade-related information (forexample, a parade_id) from the demodulating unit 1302 to control thedemultiplexer 1303 to select an RS frame of a parade including arequired mobile service. The application manager 1311 can also receivean ensemble_id to control the demultiplexer 1303 to select an RS frameof an ensemble including mobile service data to be decoded from theparade. The application manager 1311 also controls the channel manager1312 to perform channel-related operations (for example, channel mapmanagement and program table decoder operations).

The channel manager 1312 manages physical and logical channel maps andcontrols the tuner 1301 and the program table decoder 1305 to respond toa channel-related request of the viewer. The channel manager alsorequests that the program table decoder 1305 parse a channel-relatedtable of a channel to be tuned and receives the parsing results from theprogram table decoder 1305.

Demodulating Unit within Receiving System

FIG. 41 illustrates an example of a demodulating unit in a digitalbroadcast receiving system according to the present invention. Thedemodulating unit of FIG. 41 uses known data information, which isinserted in the mobile service data section and, then, transmitted bythe transmitting system, so as to perform carrier synchronizationrecovery, frame synchronization recovery, and channel equalization,thereby enhancing the receiving performance. Also the demodulating unitmay turn the power on only during a slot to which the data group of thedesignated (or desired) parade is assigned, thereby reducing powerconsumption of the receiving system.

Referring to FIG. 41, the demodulating unit includes an operationcontroller 2000, a demodulator 2002, an equalizer 2003, a known sequencedetector 2004, a block decoder 2005, and a RS frame decoder 2006. Thedemodulating unit may further include a main service data processor2008. The main service data processor 2008 may include a datadeinterleaver, a RS decoder, and a data derandomizer. The demodulatingunit may further include a signaling decoder 2013. The receiving systemalso may further include a power controller 5000 for controlling powersupply of the demodulating unit.

More specifically, a frequency of a particular channel tuned by a tunerdown converts to an intermediate frequency (IF) signal. Then, thedown-converted data 2001 outputs the down-converted IF signal to thedemodulator 2002 and the known sequence detector 2004. At this point,the down-converted data 2001 is inputted to the demodulator 2002 and theknown sequence detector 2004 via analog/digital converter ADC (notshown). The ADC converts pass-band analog IF signal into pass-banddigital IF signal.

The demodulator 2002 performs self gain control, carrier recovery, andtiming recovery processes on the inputted pass-band digital IF signal,thereby modifying the IF signal to a base-band signal. Then, thedemodulator 2002 outputs the newly created base-band signal to theequalizer 2003 and the known sequence detector 2004.

The equalizer 2003 compensates the distortion of the channel included inthe demodulated signal and then outputs the error-compensated signal tothe block decoder 2005.

At this point, the known sequence detector 2004 detects the knownsequence position information inserted by the transmitting end from theinput/output data of the demodulator 2002 (i.e., the data prior to thedemodulation process or the data after the demodulation process).Thereafter, the position information along with the symbol sequence ofthe known data, which are generated from the detected position, isoutputted to the operation controller 2000, the demodulator 2002, theequalizer 2003, and the signaling decoder 2013. Also, the known sequencedetector 2004 outputs a set of information to the block decoder 2005.This set of information is used to allow the block decoder 2005 of thereceiving system to identify the mobile service data that are processedwith additional encoding from the transmitting system and the mainservice data that are not processed with additional encoding.

In addition, although the connection status is not shown in FIG. 41, theinformation detected from the known sequence detector 2004 may be usedthroughout the entire receiving system and may also be used in the RSframe decoder 2006.

The data demodulated in the demodulator 2002 or the data equalized inthe channel equalizer 2003 is inputted to the signaling decoder 2013.The known data position information detected in the known sequencedetector 2004 is inputted to the signaling decoder 2013.

The signaling decoder 2013 extracts and decodes signaling information(e.g., TPC information, and FIC information), which inserted andtransmitted by the transmitting end, from the inputted data, the decodedsignaling information provides to blocks requiring the signalinginformation.

More specifically, the signaling decoder 2013 extracts and decodes TPCdata and FIC data, which inserted and transmitted by the transmittingend, from the equalized data, and then the decoded TPC data and FIC dataoutputs to the operation controller 2000, the known sequence detector2004, and the power controller 5000. For example, the TPC data and FICdata is inserted in a signaling information region of each data group,and then is transmitted to a receiving system.

The signaling decoder 2013 performs signaling decoding as an inverseprocess of the signaling encoder shown in FIG. 34, so as to extract TPCdata and FIC data. For example, the signaling decoder 2013 decodes theinputted data using the PCCC method and derandomizes the decoded data,thereby dividing the derandomized data into TPC data and FIC data. Atthis point, the signaling decoder 2013 performs RS-decoding on thedivided TPC data, so as to correct the errors occurring in the TPC data.Subsequently, the signaling decoder 2013 deinterleaves the divided FICdata and then performs RS-decoding on the deinterleaved FIC data, so asto correct the error occurring in the FIC data. The error-corrected TPCdata are then outputted to the operation controller 2000, the knownsequence detector 2004, and the power controller 5000.

The TPC data may also include a transmission parameter which is insertedinto the payload region of an OM packet by the service multiplexer 100,and then is transmitted to transmitter 200.

Herein, the TPC data may include RS frame information, SCCC information,M/H frame information, and so on, as shown in FIG. 35. The RS frameinformation may include RS frame mode information and RS code modeinformation. The SCCC information may include SCCC block modeinformation and SCCC outer code mode information. The M/H frameinformation may include M/H frame index information, and the TPC datamay include sub-frame count information, slot count information,parade_id information, SGN information, NoG information, and so on.

At this point, the signaling decoder 2013 can know the signalinginformation region within a data group by using the known datainformation being outputted from the known sequence detector 2004.Namely, the 1^(st) known sequence (or training sequence) is located atthe last 2 segments of the 3^(rd) M/H block (B3) within the data group.The 2^(nd) training sequence may be inserted at the 2^(nd) and 3^(rd)segments of the 4^(th) M/H block (B4). The 2^(nd) known sequence islocated at between 2^(nd) and 3^(rd) segments of the 4^(th) M/H block(B4) within the data group. Since the 2^(nd) known sequence is insertedand received next to the signaling information area, the signalingdecoder 2013 may extract and decode signaling information included inthe signaling information region from the data being outputted in thedemodulator 2002 or the channel equalizer 2003.

The power controller 5000 is inputted the M/H frame-associatedinformation from the signaling decoder 2013, and controls power of thetuner and the demodulating unit. Alternatively, the power controller5000 is inputted a power control information from the operationcontroller 2000, and controls power of the tuner and the demodulatingunit.

According to the embodiment of the present invention, the powercontroller 5000 turns the power on only during a slot to which a slot ofthe parade including user-selected mobile service is assigned. The powercontroller 5000 then turns the power off during the remaining slots.

For example, it is assumed that data groups of a 1^(st) parade withNOG=3, a 2^(nd) parade with NOG=2, and a 3^(rd) parade with NOG=3 areassigned to one M/H frame, as shown in FIG. 37. It is also assumed thatthe user has selected a mobile service included in the 1^(st) paradeusing the keypad provided on the remote controller or terminal. In thiscase, the power controller 5000 turns the power on during a slot thatdata groups of the 1^(st) parade is assigned, as shown in FIG. 37, andturns the power off during the remaining slots, thereby reducing powerconsumption.

The demodulator 2002 uses the known data symbol sequence during thetiming and/or carrier recovery, thereby enhancing the demodulatingperformance. Similarly, the equalizer 2003 uses the known data so as toenhance the equalizing performance. Moreover, the decoding result of theblock decoder 2005 may be fed-back to the equalizer 2003, therebyenhancing the equalizing performance.

Demodulator and Known Sequence Detector

At this point, the transmitting system may receive a data frame (or VSBframe) including a data group which known data sequence (or trainingsequence) is periodically inserted therein, as shown in FIG. 5. Herein,the data group is divided into regions A to D, as shown in FIG. 5. Morespecifically, in the example of the present invention, each region A, B,C, and D are further divided into M/H blocks B4 to B7, M/H blocks B3 andB8, M/H blocks B2 and B9, M/H blocks B1 and B10, respectively.

Referring to FIG. 38 and FIG. 39, known data sequence having the samepattern are included in each known data section that is beingperiodically inserted. Herein, the length of the known data sequencehaving identical data patterns may be either equal to or different fromthe length of the entire (or total) known data sequence of thecorresponding known data section (or block). If the two lengths aredifferent from one another, the length of the entire known data sequenceshould be longer than the length of the known data sequence havingidentical data patterns. In this case, the same known data sequences areincluded in the entire known data sequence.

As described above, when the known data are periodically insertedin-between the mobile service data, the channel equalizer of thereceiving system may use the known data as training sequences, which maybe used as accurate discriminant values. According to another embodimentof the present invention, the channel equalizer estimates a channelimpulse response. Herein, the known data may be used in the process.According to yet another embodiment of the present invention, thechannel equalizer may use the known data for updating filtercoefficients (i.e., equalization coefficients).

Meanwhile, when known data sequence having the same pattern isperiodically inserted, each known data sequence may be used as a guardinterval in a channel equalizer according to the present invention.Herein, the guard interval prevents interference that occurs betweenblocks due to a multiple path channel. This is because the known datasequence located behind a mobile service data section (i.e., data block)may be considered as being copied in front of the mobile service datasection.

The above-described structure is referred to as a cyclic prefix. Thisstructure provides circular convolution in a time domain between a datablock transmitted from the transmitting system and a channel impulseresponse. Accordingly, this facilitates the channel equalizer of thereceiving system to perform channel equalization in a frequency domainby using a fast fourier transform (FFT) and an inverse fast fouriertransform (IFFT).

More specifically, when viewed in the frequency domain, the data blockreceived by the receiving system is expressed as a multiplication of thedata block and the channel impulse response. Therefore, when performingthe channel equalization, by multiplying the inverse of the channel inthe frequency domain, the channel equalization may be performed moreeasily.

The known sequence detector 2004 detects the position of the known databeing periodically inserted and transmitted as described above. At thesame time, the known sequence detector 2004 may also estimate initialfrequency offset during the process of detecting known data. In thiscase, the demodulator 2002 may estimate with more accuracy carrierfrequency offset from the information on the known data positioninformation and initial frequency offset estimation value, therebycompensating the estimated carrier frequency offset.

Meanwhile, when known data is transmitted, as shown in FIG. 5, the knownsequence detector 2004 detects a position of second known data region byusing known data of the second known data region that the same patternis repeated twice.

At this point, since the known sequence detector 2004 is well-informedof the data group structure, when the position of the second known dataregion is detected, the known sequence detector 2004 can estimatepositions of the first, third, fourth, fifth, and sixth known dataregions of a corresponding data group by counting symbols or segmentsbased upon the second known data region position. If the correspondingdata group is a data group including field synchronization segment, theknown sequence detector 2004 can estimate the position of the fieldsynchronization segment of the corresponding data group, which ispositioned chronologically before the second known data region, bycounting symbols or segments based upon the second known data regionposition. Also, the known sequence detector 2004 may estimate the knowndata position information and the field synchronization positioninformation from the parade including mobile service selected by a userbased on the M/H frame-associated information outputted from thesignaling decoder 2013.

At least one of the estimated known data poison information and fieldsynchronization information is provided to the demodulator 2002, thechannel equalizer 2003, the signaling decoder 2013, and the operationcontroller 2000.

Also, the known sequence detector 2004 may estimate initial frequencyoffset by using known data inserted in the second known data region(i.e., ACQ known data region). In this case, the demodulator 2002 mayestimate with more accuracy carrier frequency offset from theinformation on the known data position information and initial frequencyoffset estimation value, thereby compensating the estimated carrierfrequency offset.

Operation Controller

The operation controller 2000 receives the known data positioninformation and the transmission parameter information and then forwardsM/H frame time information, a presence or non-presence of a data groupof a selected parade, position information of known data within the datagroup, power control information and the like to each block of thedemodulating unit. The operation controller 2000, as shown in FIG. 41,controls operations of the demodulator 2002, the channel equalizer 2003,the block decoder 2005 and the RS frame decoder 2006. And, the operationcontroller 2000 is able to overall operations of the demodulating unit(not shown in the drawing). Moreover, the operation controller 2000 canbe implemented with the separate block or can be included within aprescribed one of the blocks of the demodulating unit shown in FIG. 41.

FIG. 42 is an overall block diagram of an operation controller 2000.

Referring to FIG. 42, the operation controller 2000 can include a paradeID checker 3101, a frame synchronizer 3102, a parade mapper 3103, agroup controller 3104 and a known sequence indication controller 3105.

The operation controller 2000 receives known data position informationfrom the known sequence detector 2004 and receives transmissionparameter information from the signaling decoder 2013. The operationcontroller 2000 then generates a control signal necessary for ademodulating unit of a receiving system. For instance, the known dataposition information detected by the known sequence detector 2004 isinputted to the known sequence indication controller 3105. And, thetransmission parameter information (i.e., TPC data) decoded by thesignaling decoder 2013 is inputted to the parade ID checker 3101.

The parade ID checker 3101 compares a parade ID (parade ID selected by auser) contained in the user control signal to a parade ID inputted fromthe signaling decoder 2013. If the two parade IDs are not identical toeach other, the parade ID checker stands by until a next transmissionparameter is inputted from the signaling decoder 2013.

If the two parade IDs are identical to each other, the parade ID checker3101 outputs the transmission parameter information to the blocks withinthe operation controller 2000 and the overall system.

If it is checked that the parade ID in the transmission parameterinformation inputted to the parade ID checker 3101 is identical to theparade ID selected by a user, the parade ID checker 3101 outputsstarting_group_number (SGN) and number_of_groups (NOG) to the parademapper 3103, outputs sub_frame_number, slot_number andparade_repetition_cycle PRC) to the frame synchronizer 3102, outputsSCCC_block_mode, SCCC_outer_code_mode_A, SCCC_outer_code_mode_B,SCCC_outer_code_mode_C and SCCC_outer_code_mode_D to the block decoder2005, and outputs RS_frame_mode, RS_code_mode_primary andRs_code_mode_secondary to the RS frame decoder 2006.

The parade mapper 3103 receives the SGN and the NOG from the parade IDchecker as inputs, decides a data group is carried by which one ofsixteen slots within a Sub-frame, and then outputs the correspondinginformation. Data group number transmitted every sub-frame is set to aninteger consecutive between SGN and (SGN+NOG−1). For instance, if SGN=3and NOG=4, four groups, of which group numbers are 3, 4, 5 and 6, aretransmitted for the corresponding sub-frames, respectively. The parademapper finds a slot number j for transmitting a data group according toEquation 1 with a group number i obtained from SGN and NOG.

In the above example, in case of SGN=3 and NOG=4, if they are insertedin Equation 1, slot numbers of groups transmitted according to the aboveformula sequentially become 12, 2, 6 and 10.

The parade mapper 3103 then outputs the found slot number information.

For example of outputting slot numbers, a method of using a bit vectorhaving 16 bits is available.

A bit vector SNi (i=0˜15) can be set to 1 if there exists a grouptransmitted for an i^(th) slot. A bit vector SNi (i=0˜15) can be set to0 if a group transmitted for an i^(th) slot does not exist. And, thisbit vector can be outputted as slot number information.

The frame synchronizer 3102 receives the sub_frame_number, slot-numberand PRC from the parade ID checker and then sends slot_counter andframe_mask signals as outputs. The slot_counter is the signal indicatinga slot_number at a current timing point at which a receiver isoperating. And, the frame_mask is the signal indicating whether acorresponding parade is transmitted for a current frame. The framesynchronizer 3102 performs a process for initializing slot_counter,sub_frame_number and frame_counter in receiving signaling informationinitially. A counter value of a current timing point is generated fromadding a delayed slot number L according to a time taken to decodesignaling from demodulation together with the signaling informationinputted in this process. After completion of the initializationprocess, slot_counter is updated every single slot period, updatessub_frame_counter every period of the slot_counter value, and updatesframe_counter every period of the sub_frame_counter. By referring to theframe_counter information and the PRC information, a frame_mask signalis generated. For example, if a corresponding parade is beingtransmitted for a current frame, ‘1’ is outputted as the frame_mask.Otherwise, it is able to output ‘0’.

The group controller 3104 receives the slot number information from theparade mapper 3103. The group controller 3104 receives the slot_counterand frame_mask information from the frame synchronizer 3102. The groupcontroller 3104 then outputs group_presence_indicator indicating whetheran M/H group is being transmitted. For instance, if the slot numberinformation inputted from the parade mapper 3103 corresponds to 12, 2, 6and 10, when the frame_mask information inputted from the framesynchronizer 3102 is 1 and the slot_counter inputted from the framesynchronizer 3102 includes 2, 6, 10 and 12, ‘1’ is outputted as thegroup_presence_indicator. Otherwise, it is able to output 0.

The known sequence indication controller 3105 outputs positioninformation of another known data, group start position information andthe like with position information of specific inputted known data. Inthis case, since the known data are present at a previously appointedposition within the data group, if position data of one of a pluralityof known data sequences, it is able to know data position information ofanother known sequence, data group start position information and thelike. The known sequence indication controller 3105 can output knowndata and data group position information necessary for the demodulatingunit of the receiving system using the group_presence_indicatorinformation only if the data group is transmitted. Alternatively, theknown sequence detector 2004 can perform operations of the knownsequence indication controller 3105.

Channel Equalizer

The data demodulated by the demodulator 2002 by using the known data areinputted to the equalizer 2003. Additionally, the demodulated data mayalso be inputted to the known sequence detector 2004. At this point, adata group that is inputted for the equalization process may be dividedinto region A to region D, as shown in FIG. 5. More specifically,according to the embodiment of the present invention, region A includesM/H block B4 to M/H block B7, region B includes M/H block B3 and M/Hblock B8, region C includes M/H block B2 and M/H block B9, and region Dincludes M/H block B1 and M/H block B10. In other words, one data groupis divided into M/H blocks from B1 to B10, each M/H block having thelength of 16 segments. Also, a long training sequence (i.e., known datasequence) is inserted at the starting portion of the M/H blocks B4 toB8. Furthermore, two data groups may be allocated (or assigned) to oneVSB field. In this case, field synchronization data are positioned inthe 37^(th) segment of one of the two data groups.

The present invention may use known data, which have position andcontent information based upon an agreement between the transmittingsystem and the receiving system, and/or field synchronization data forthe channel equalization process.

The channel equalizer 2003 may perform channel equalization using aplurality of methods. According to the present invention, the channelequalizer 2003 uses known data and/or field synchronization data, so asto estimate a channel impulse response (CIR), thereby performing channelequalization.

Most particularly, an example of estimating the CIR in accordance witheach region within the data group, which is hierarchically divided andtransmitted from the transmitting system, and applying each CIRdifferently will also be described herein.

At this point, a data group can be assigned and transmitted a maximumthe number of 4 in a VSB frame in the transmitting system. In this case,all data group do not include field synchronization data. In the presentinvention, the data group including the field synchronization dataperforms channel-equalization using the field synchronization data andknown data. And the data group not including the field synchronizationdata performs channel-equalization using the known data.

For example, the data of the M/H block B3 including the fieldsynchronization data performs channel-equalization using the CIRcalculated from the field synchronization data area and the CIRcalculated from the first known data area. Also, the data of the M/Hblocks B1 and B2 performs channel-equalization using the CIR calculatedfrom the field synchronization data area and the CIR calculated from thefirst known data area. Meanwhile, the data of the M/H blocks B1 to B3not including the field synchronization data performschannel-equalization using CIRS calculated from the first known dataarea and the third known data area.

As described above, the present invention uses the CIR estimated fromthe known data region in order to perform channel equalization on datawithin the data group. At this point, each of the estimated CIRs may bedirectly used in accordance with the characteristics of each regionwithin the data group. Alternatively, a plurality of the estimated CIRsmay also be either interpolated or extrapolated so as to create a newCIR, which is then used for the channel equalization process.

Herein, when a value F(Q) of a function F(x) at a particular point Q anda value F(S) of the function F(x) at another particular point S areknown, interpolation refers to estimating a function value of a pointwithin the section between points Q and S. Linear interpolationcorresponds to the simplest form among a wide range of interpolationoperations.

FIG. 43 illustrates an example of linear interpolation. Morespecifically, in a random function F(x), when given the values F(Q) andF(S) each from points x=Q and x=S, respectively, the approximate value{circumflex over (F)}(P) of the F(x) function at point x=P may beestimated by using Equation 7 below. In other words, since the values ofF(Q) and F(S) respective to each point x=Q and x=S are known (or given),a straight line passing through the two points may be calculated so asto obtain the approximate value {circumflex over (F)}(P) of thecorresponding function value at point P. At this point, the straightline passing through points (Q,F(Q)) and (S,F(S)) may be obtained byusing Equation 7 below.

$\begin{matrix}{{\hat{F}(x)} = {{\frac{{F(S)} - {F(Q)}}{S - Q}( {x - Q} )} + {F(Q)}}} & {{Equation}\mspace{14mu} 7}\end{matrix}$

Accordingly, Equation 8 below shows the process of substituting p for xin Equation 7, so as to calculate the approximate value {circumflex over(F)}(P) of the function value at point P.

$\begin{matrix}{{{\hat{F}(P)} = {{\frac{{F(S)} - {F(Q)}}{S - Q}( {P - Q} )} + {F(Q)}}}{{\hat{F}(P)} = {{\frac{S - P}{S - Q}{F(Q)}} + {\frac{P - Q}{S - Q}{F(S)}}}}} & {{Equation}\mspace{14mu} 8}\end{matrix}$

The linear interpolation method of Equation 8 is merely the simplestexample of many other linear interpolation methods. Therefore, since anyother linear interpolation method may be used, the present inventionwill not be limited only to the examples given herein.

Alternatively, when a value F(Q) of a function F(x) at a particularpoint Q and a value F(S) of the function F(x) at another particularpoint S are known (or given), extrapolation refers to estimating afunction value of a point outside of the section between points Q and S.Herein, the simplest form of extrapolation corresponds to linearextrapolation.

FIG. 44 illustrates an example of linear extrapolation. As describedabove, for linear extrapolation as well as linear interpolation, in arandom function F(x), when given the values F(Q) and F(S) each frompoints x=Q and x=S, respectively, the approximate value {circumflex over(F)}(P) of the corresponding function value at point P may be obtainedby calculating a straight line passing through the two points. Herein,linear extrapolation is the simplest form among a wide range ofextrapolation operations. Similarly, the linear extrapolation describedherein is merely exemplary among a wide range of possible extrapolationmethods. And, therefore, the present invention is not limited only tothe examples set forth herein.

FIG. 45 illustrates a block diagram of a channel equalizer according toan embodiment of the present invention. Referring to FIG. 45, thechannel equalizer includes a first frequency domain converter 4100, achannel estimator 4110, a second frequency domain converter 4121, acoefficient calculator 4122, a distortion compensator 4130, and a timedomain converter 4140. Herein, the channel equalizer may further includea remaining carrier phase error remover, a noise canceller (NC), and adecision unit.

The first frequency domain converter 4100 includes an overlap unit 4101overlapping inputted data, and a fast fourier transform (FFT) unit 4102converting the data outputted from the overlap unit 4101 to frequencydomain data.

The channel estimator 4110 includes a CIR estimator 4111, a firstcleaner 4113, a CIR calculator 4114, a second cleaner, and azero-padding unit. herein, the channel estimator 4110 may furtherinclude a phase compensator compensating a phase of the CIR whichestimated in the CIR estimator 4111.

The second frequency domain converter 4121 includes a fast fouriertransform (FFT) unit converting the CIR being outputted from the channelestimator 4110 to frequency domain CIR.

The time domain converter 4140 includes an IFFT unit 4141 converting thedata having the distortion compensated by the distortion compensator4130 to time domain data, and a save unit 4142 extracting only validdata from the data outputted from the IFFT unit 4141. The output datafrom the save unit 4142 corresponds to the channel-equalized data.

If the remaining carrier phase error remover is connected to an outputterminal of the time domain converter 4140, the remaining carrier phaseerror remover estimates the remaining carrier phase error included inthe channel-equalized data, thereby removing the estimated error. If thenoise remover is connected to an output terminal of the time domainconverter 4140, the noise remover estimates noise included in thechannel-equalized data, thereby removing the estimated noise.

More specifically, the receiving data demodulated in FIG. 45 areoverlapped by the overlap unit 4101 of the first frequency domainconverter 4100 at a pre-determined overlapping ratio, which are thenoutputted to the FFT unit 4102. The FFT unit 4102 converts theoverlapped time domain data to overlapped frequency domain data throughby processing the data with FFT. Then, the converted data are outputtedto the distortion compensator 4130.

The distortion compensator 4130 performs a complex number multiplicationon the overlapped frequency domain data outputted from the FFT unit 4102included in the first frequency domain converter 4100 and theequalization coefficient calculated from the coefficient calculator4122, thereby compensating the channel distortion of the overlapped dataoutputted from the FFT unit 4102. Thereafter, the compensated data areoutputted to the IFFT unit 4141 of the time domain converter 4140. TheIFFT unit 4141 performs IFFT on the overlapped data having the channeldistortion compensated, thereby converting the overlapped data to timedomain data, which are then outputted to the save unit 4142. The saveunit 4142 extracts valid data from the data of the channel-equalized andoverlapped in the time domain, and outputs the extracted valid data.

Meanwhile, the received data are inputted to the overlap unit 4101 ofthe first frequency domain converter 4100 included in the channelequalizer and, at the same time, inputted to the CIR estimator 4111 ofthe channel estimator 4110.

The CIR estimator 4111 uses a training sequence, for example, data beinginputted during the known data section and the known data in order toestimate the CIR. If the data to be channel-equalizing is the datawithin the data group including field synchronization data, the trainingsequence using in the CIR estimator 4111 may become the fieldsynchronization data and known data. Meanwhile, if the data to bechannel-equalizing is the data within the data group not including fieldsynchronization data, the training sequence using in the CIR estimator4111 may become only the known data.

For example, the CIR estimator 4111 estimates CIR using the known datacorrespond to reference known data generated during the known datasection by the receiving system in accordance with an agreement betweenthe receiving system and the transmitting system. For this, the CIRestimator 4111 is provided known data position information from theknown sequence detector 2004. Also the CIR estimator 4111 may beprovided field synchronization position information from the knownsequence detector 2004.

The estimated CIR passes through the first cleaner (or pre-CIR cleaner)4113 or bypasses the first cleaner 4113, thereby being inputted to theCIR calculator (or CIR interpolator-extrapolator) 4114. The CIRcalculator 4114 either interpolates or extrapolates an estimated CIR,which is then outputted to the second cleaner (or post-CIR cleaner)4115.

The first cleaner 4113 may or may not operate depending upon whether theCIR calculator 4114 interpolates or extrapolates the estimated CIR. Forexample, if the CIR calculator 4114 interpolates the estimated CIR, thefirst cleaner 4113 does not operate. Conversely, if the CIR calculator4114 extrapolates the estimated CIR, the first cleaner 4113 operates.

More specifically, the CIR estimated from the known data includes achannel element that is to be obtained as well as a jitter elementcaused by noise. Since such jitter element deteriorates the performanceof the equalizer, it preferable that a coefficient calculator 4122removes the jitter element before using the estimated CIR. Therefore,according to the embodiment of the present invention, each of the firstand second cleaners 4113 and 4115 removes a portion of the estimated CIRhaving a power level lower than the predetermined threshold value (i.e.,so that the estimated CIR becomes equal to ‘0’). Herein, this removalprocess will be referred to as a “CIR cleaning” process.

The CIR calculator 4114 performs CIR interpolation by multiplying CIRsestimated from the CIR estimator 4111 by each of coefficients, therebyadding the multiplied values. At this point, some of the noise elementsof the CIR may be added to one another, thereby being cancelled.Therefore, when the CIR calculator 4114 performs CIR interpolation, theoriginal (or initial) CIR having noise elements remaining therein. Inother words, when the CIR calculator 4114 performs CIR interpolation,the estimated CIR bypasses the first cleaner 4113 and is inputted to theCIR calculator 4114. Subsequently, the second cleaner 4115 cleans theCIR interpolated by the CIR interpolator-extrapolator 4114.

Conversely, the CIR calculator 4114 performs CIR extrapolation by usinga difference value between two CIRs, so as to estimate a CIR positionedoutside of the two CIRs. Therefore, in this case, the noise element israther amplified. Accordingly, when the CIR calculator 4114 performs CIRextrapolation, the CIR cleaned by the first cleaner 4113 is used. Morespecifically, when the CIR calculator 4114 performs CIR extrapolation,the extrapolated CIR passes through the second cleaner 4115, therebybeing inputted to the zero-padding unit 4116.

Meanwhile, when a second frequency domain converter (or fast fouriertransform (FFT2)) 4121 converts the CIR, which has been cleaned andoutputted from the second cleaner 4115, to a frequency domain, thelength and of the inputted CIR and the FFT size may not match (or beidentical to one another). In other words, the CIR length may be smallerthan the FFT size. In this case, the zero-padding unit 4116 adds anumber of zeros ‘0’s corresponding to the difference between the FFTsize and the CIR length to the inputted CIR, thereby outputting theprocessed CIR to the second frequency domain converter (FFT2) 4121.Herein, the zero-padded CIR may correspond to one of the interpolatedCIR, extrapolated CIR, and the CIR estimated in the known data section.

The second frequency domain converter 4121 performs FFT on the CIR beingoutputted from the zero padding unit 4116, thereby converting the CIR toa frequency domain CIR. Then, the second frequency domain converter 4121outputs the converted CIR to the coefficient calculator 4122.

The coefficient calculator 4122 uses the frequency domain CIR beingoutputted from the second frequency domain converter 4121 to calculatethe equalization coefficient. Then, the coefficient calculator 4122outputs the calculated coefficient to the distortion compensator 4130.Herein, for example, the coefficient calculator 4122 calculates achannel equalization coefficient of the frequency domain that canprovide minimum mean square error (MMSE) from the CIR of the frequencydomain, which is outputted to the distortion compensator 4130.

The distortion compensator 4130 performs a complex number multiplicationon the overlapped data of the frequency domain being outputted from theFFT unit 4102 of the first frequency domain converter 4100 and theequalization coefficient calculated by the coefficient calculator 4122,thereby compensating the channel distortion of the overlapped data beingoutputted from the FFT unit 4102.

Block Decoder

Meanwhile, if the data being inputted to the block decoder 2005, afterbeing channel-equalized by the equalizer 2003, correspond to the datahaving both block encoding and trellis encoding performed thereon (i.e.,the data within the RS frame, the signaling information data, etc.) bythe transmitting system, trellis decoding and block decoding processesare performed on the inputted data as inverse processes of thetransmitting system. Alternatively, if the data being inputted to theblock decoder 2005 correspond to the data having only trellis encodingperformed thereon (i.e., the main service data), and not the blockencoding, only the trellis decoding process is performed on the inputteddata as the inverse process of the transmitting system.

The trellis decoded and block decoded data by the block decoder 2005 arethen outputted to the RS frame decoder 2006. More specifically, theblock decoder 2005 removes the known data, data used for trellisinitialization, and signaling information data, MPEG header, which havebeen inserted in the data group, and the RS parity data, which have beenadded by the RS encoder/non-systematic RS encoder or non-systematic RSencoder of the transmitting system.

Then, the block decoder 2005 outputs the processed data to the RS framedecoder 2006. Herein, the removal of the data may be performed beforethe block decoding process, or may be performed during or after theblock decoding process.

Meanwhile, the data trellis-decoded by the block decoder 2005 areoutputted to the data deinterleaver of the main service data processor2008. At this point, the data being trellis-decoded by the block decoder2005 and outputted to the data deinterleaver may not only include themain service data but may also include the data within the RS frame andthe signaling information. Furthermore, the RS parity data that areadded by the transmitting system after the pre-processor 230 may also beincluded in the data being outputted to the data deinterleaver.

According to another embodiment of the present invention, data that arenot processed with block decoding and only processed with trellisencoding by the transmitting system may directly bypass the blockdecoder 2005 so as to be outputted to the data deinterleaver. In thiscase, a trellis decoder should be provided before the datadeinterleaver. More specifically, if the inputted data correspond to thedata having only trellis encoding performed thereon and not blockencoding, the block decoder 2005 performs Viterbi (or trellis) decodingon the inputted data so as to output a hard decision value or to performa hard-decision on a soft decision value, thereby outputting the result.

Meanwhile, if the inputted data correspond to the data having both blockencoding process and trellis encoding process performed thereon, theblock decoder 2005 outputs a soft decision value with respect to theinputted data.

In other words, if the inputted data correspond to data being processedwith block encoding by the block processor 302 and being processed withtrellis encoding by the trellis encoding module 256, in the transmittingsystem, the block decoder 2005 performs a decoding process and a trellisdecoding process on the inputted data as inverse processes of thetransmitting system. At this point, the RS frame encoder of thepre-processor included in the transmitting system may be viewed as anouter (or external) encoder. And, the trellis encoder may be viewed asan inner (or internal) encoder. When decoding such concatenated codes,in order to allow the block decoder 2005 to maximize its performance ofdecoding externally encoded data, the decoder of the internal codeshould output a soft decision value.

FIG. 46 illustrates a detailed block diagram of the block decoder 2005according to an embodiment of the present invention. Referring to FIG.46, the block decoder 2005 includes a feedback controller 4010, an inputbuffer 4011, a trellis decoding unit (or 12-way trellis coded modulation(TCM) decoder or inner decoder) 4012, a symbol-byte converter 4013, anouter block extractor 4014, a feedback deformatter 4015, a symboldeinterleaver 4016, an outer symbol mapper 4017, a symbol decoder 4018,an inner symbol mapper 4019, a symbol interleaver 4020, a feedbackformatter 4021, and an output buffer 4022. Herein, just as in thetransmitting system, the trellis decoding unit 4012 may be viewed as aninner (or internal) decoder. And, the symbol decoder 4018 may be viewedas an outer (or external) decoder.

The input buffer 4011 temporarily stores the mobile service data symbolsbeing channel-equalized and outputted from the equalizer 2003. (Herein,the mobile service data symbols may include symbols corresponding to thesignaling information, RS parity data symbols and CRC data symbols addedduring the encoding process of the RS frame.) Thereafter, the inputbuffer 4011 repeatedly outputs the stored symbols for M number of timesto the trellis decoding unit 4012 in a turbo block (TDL) size requiredfor the turbo decoding process.

The turbo decoding length (TDL) may also be referred to as a turboblock. Herein, a TDL should include at least one SCCC block size.Therefore, as defined in FIG. 5, when it is assumed that one M/H blockis a 16-segment unit, and that a combination of 10 M/H blocks form oneSCCC block, a TDL should be equal to or larger than the maximum possiblecombination size. For example, when it is assumed that 2 M/H blocks formone SCCC block, the TDL may be equal to or larger than 32 segments(i.e., 828×32=26496 symbols). Herein, M indicates a number ofrepetitions for turbo-decoding pre-decided by the feed-back controller4010.

Also, M represents a number of repetitions of the turbo decodingprocess, the number being predetermined by the feedback controller 4010.

Additionally, among the values of symbols being channel-equalized andoutputted from the equalizer 2003, the input symbol values correspondingto a section having no mobile service data symbols (including RS paritydata symbols during RS frame encoding and CRC data symbols) includedtherein, bypass the input buffer 4011 without being stored. Morespecifically, since trellis-encoding is performed on input symbol valuesof a section wherein SCCC block-encoding has not been performed, theinput buffer 4011 inputs the inputted symbol values of the correspondingsection directly to the trellis encoding module 4012 without performingany storage, repetition, and output processes. The storage, repetition,and output processes of the input buffer 4011 are controlled by thefeedback controller 4010. Herein, the feedback controller 4010 refers toSCCC-associated information (e.g., SCCC block mode and SCCC outer codemode), which are outputted from the signaling decoder 2013 or theoperation controller 2000, in order to control the storage and outputprocesses of the input buffer 4011.

The trellis decoding unit 4012 includes a 12-way TCM decoder. Herein,the trellis decoding unit 4012 performs 12-way trellis decoding asinverse processes of the 12-way trellis encoder.

More specifically, the trellis decoding unit 4012 receives a number ofoutput symbols of the input buffer 4011 and soft-decision values of thefeedback formatter 4021 equivalent to each TDL, so as to perform the TCMdecoding process.

At this point, based upon the control of the feedback controller 4010,the soft-decision values outputted from the feedback formatter 4021 arematched with a number of mobile service data symbol places so as to bein a one-to-one (1:1) correspondence. Herein, the number of mobileservice data symbol places is equivalent to the TDL being outputted fromthe input buffer 4011.

More specifically, the mobile service data being outputted from theinput buffer 4011 are matched with the turbo decoded data beinginputted, so that each respective data place can correspond with oneanother. Thereafter, the matched data are outputted to the trellisdecoding unit 4012. For example, if the turbo decoded data correspond tothe third symbol within the turbo block, the corresponding symbol (ordata) is matched with the third symbol included in the turbo block,which is outputted from the input buffer 4011. Subsequently, the matchedsymbol (or data) is outputted to the trellis decoding unit 4012.

In order to do so, while the regressive turbo decoding is in process,the feedback controller 4010 controls the input buffer 4011 so that theinput buffer 4011 stores the corresponding turbo block data. Also, bydelaying data (or symbols), the soft decision value (e.g., LLR) of thesymbol outputted from the symbol interleaver 4020 and the symbol of theinput buffer 4011 corresponding to the same place (or position) withinthe block of the output symbol are matched with one another to be in aone-to-one correspondence. Thereafter, the matched symbols arecontrolled so that they can be inputted to the TCM decoder through therespective path. This process is repeated for a predetermined number ofturbo decoding cycle periods. Then, the data of the next turbo block areoutputted from the input buffer 4011, thereby repeating the turbodecoding process.

The output of the trellis decoding unit 4012 signifies a degree ofreliability of the transmission bits configuring each symbol. Forexample, in the transmitting system, since the input data of the trellisencoding module correspond to two bits as one symbol, a log likelihoodratio (LLR) between the likelihood of a bit having the value of ‘1’ andthe likelihood of the bit having the value of ‘0’ may be respectivelyoutputted (in bit units) to the upper bit and the lower bit. Herein, thelog likelihood ratio corresponds to a log value for the ratio betweenthe likelihood of a bit having the value of ‘1’ and the likelihood ofthe bit having the value of ‘0’. Alternatively, a LLR for the likelihoodof 2 bits (i.e., one symbol) being equal to “00”, “01”, “10”, and “11”may be respectively outputted (in symbol units) to all 4 combinations ofbits (i.e., 00, 01, 10, 11). Consequently, this becomes the softdecision value that indicates the degree of reliability of thetransmission bits configuring each symbol. A maximum a posterioriprobability (MAP) or a soft-out Viterbi algorithm (SOYA) may be used asa decoding algorithm of each TCM decoder within the trellis decodingunit 4012.

The output of the trellis decoding unit 4012 is inputted to thesymbol-byte converter 4013 and the outer block extractor 4014.

The symbol-byte converter 4013 performs a hard-decision process of thesoft decision value that is trellis decoded and outputted from thetrellis decoding unit 4012. Thereafter, the symbol-byte converter 4013groups 4 symbols into byte units, which are then outputted to the datadeinterleaver of the main service data processor 2008 of FIG. 41. Morespecifically, the symbol-byte converter 4013 performs hard-decision inbit units on the soft decision value of the symbol outputted from thetrellis decoding unit 4012. Therefore, the data processed withhard-decision and outputted in bit units from the symbol-byte converter4013 not only include main service data, but may also include mobileservice data, known data, RS parity data, and MPEG headers.

Among the soft decision values of TDL size of the trellis decoding unit4012, the outer block extractor 4014 identifies the soft decision valuesof B size of corresponding to the mobile service data symbols (whereinsymbols corresponding to signaling information, RS parity data symbolsthat are added during the encoding of the RS frame, and CRC data symbolsare included) and outputs the identified soft decision values to thefeedback deformatter 4015.

The feedback deformatter 4015 changes the processing order of the softdecision values corresponding to the mobile service data symbols. Thisis an inverse process of an initial change in the processing order ofthe mobile service data symbols, which are generated during anintermediate step, wherein the output symbols outputted from the blockprocessor 302 of the transmitting system are being inputted to thetrellis encoding module 256 (e.g., when the symbols pass through thegroup formatter, the data deinterleaver, the packet formatter, and thedata interleaver). Thereafter, the feedback deformatter 2015 performsreordering of the process order of soft decision values corresponding tothe mobile service data symbols and, then, outputs the processed mobileservice data symbols to the symbol deinterleaver 4016.

This is because a plurality of blocks exist between the block processor302 and the trellis encoding module 256, and because, due to theseblocks, the order of the mobile service data symbols being outputtedfrom the block processor 302 and the order of the mobile service datasymbols being inputted to the trellis encoding module 256 are notidentical to one another. Therefore, the feedback deformatter 4015reorders (or rearranges) the order of the mobile service data symbolsbeing outputted from the outer block extractor 4014, so that the orderof the mobile service data symbols being inputted to the symboldeinterleaver 4016 matches the order of the mobile service data symbolsoutputted from the block processor 302 of the transmitting system. Thereordering process may be embodied as one of software, middleware, andhardware.

The symbol deinterleaver 4016 performs deinterleaving on the mobileservice data symbols having their processing orders changed andoutputted from the feedback deformatter 4015, as an inverse process ofthe symbol interleaving process of the symbol interleaver 514 includedin the transmitting system. The size of the block used by the symboldeinterleaver 4016 during the deinterleaving process is identical tointerleaving size of an actual symbol (i.e., B) of the symbolinterleaver 514, which is included in the transmitting system. This isbecause the turbo decoding process is performed between the trellisdecoding unit 4012 and the symbol decoder 4018. Both the input andoutput of the symbol deinterleaver 4016 correspond to soft decisionvalues, and the deinterleaved soft decision values are outputted to theouter symbol mapper 4017.

The operations of the outer symbol mapper 4017 may vary depending uponthe structure and coding rate of the convolution encoder 513 included inthe transmitting system. For example, when data are 1/2-rate encoded bythe convolution encoder 513 and then transmitted, the outer symbolmapper 4017 directly outputs the input data without modification. Inanother example, when data are 1/4-rate encoded by the convolutionencoder 513 and then transmitted, the outer symbol mapper 4017 convertsthe input data so that it can match the input data format of the symboldecoder 4018. For this, the outer symbol mapper 4017 may be inputtedSCCC-associated information (i.e., SCCC block mode and SCCC outer codemode) from the signaling decoder 2013. Then, the outer symbol mapper4017 outputs the converted data to the symbol decoder 4018.

The symbol decoder 4018 (i.e., the outer decoder) receives the dataoutputted from the outer symbol mapper 4017 and performs symbol decodingas an inverse process of the convolution encoder 513 included in thetransmitting system. At this point, two different soft decision valuesare outputted from the symbol decoder 4018. One of the outputted softdecision values corresponds to a soft decision value matching the outputsymbol of the convolution encoder 513 (hereinafter referred to as a“first decision value”). The other one of the outputted soft decisionvalues corresponds to a soft decision value matching the input bit ofthe convolution encoder 513 (hereinafter referred to as a “seconddecision value”).

More specifically, the first decision value represents a degree ofreliability the output symbol (i.e., 2 bits) of the convolution encoder513. Herein, the first soft decision value may output (in bit units) aLLR between the likelihood of 1 bit being equal to ‘1’ and thelikelihood of 1 bit being equal to ‘0’ with respect to each of the upperbit and lower bit, which configures a symbol. Alternatively, the firstsoft decision value may also output (in symbol units) a LLR for thelikelihood of 2 bits being equal to “00”, “01”, “10”, and “11” withrespect to all possible combinations. The first soft decision value isfed-back to the trellis decoding unit 4012 through the inner symbolmapper 4019, the symbol interleaver 4020, and the feedback formatter4021. On the other hand, the second soft decision value indicates adegree of reliability the input bit of the convolution encoder 513included in the transmitting system. Herein, the second soft decisionvalue is represented as the LLR between the likelihood of 1 bit beingequal to ‘1’ and the likelihood of 1 bit being equal to ‘0’. Thereafter,the second soft decision value is outputted to the outer buffer 4022. Inthis case, a maximum a posteriori probability (MAP) or a soft-outViterbi algorithm (SOYA) may be used as the decoding algorithm of thesymbol decoder 4018.

The first soft decision value that is outputted from the symbol decoder4018 is inputted to the inner symbol mapper 4019. The inner symbolmapper 4019 converts the first soft decision value to a data formatcorresponding the input data of the trellis decoding unit 4012.Thereafter, the inner symbol mapper 4019 outputs the converted softdecision value to the symbol interleaver 4020. The operations of theinner symbol mapper 4019 may also vary depending upon the structure andcoding rate of the convolution encoder 513 included in the transmittingsystem.

The symbol interleaver 4020 performs symbol interleaving, as shown inFIG. 30, on the first soft decision value that is outputted from theinner symbol mapper 4019. Then, the symbol interleaver 4020 outputs thesymbol-interleaved first soft decision value to the feedback formatter4021. Herein, the output of the symbol interleaver 4020 also correspondsto a soft decision value.

With respect to the changed processing order of the soft decision valuescorresponding to the symbols that are generated during an intermediatestep, wherein the output symbols outputted from the block processor 302of the transmitting system are being inputted to the trellis encodingmodule (e.g., when the symbols pass through the group formatter, thedata deinterleaver, the packet formatter, the RS encoder, and the datainterleaver), the feedback formatter 4021 alters (or changes) the orderof the output values outputted from the symbol interleaver 4020.Subsequently, the feedback formatter 4020 outputs values to the trellisdecoding unit 4012 in the changed order. The reordering process of thefeedback formatter 4021 may configure at least one of software,hardware, and middleware.

The soft decision values outputted from the symbol interleaver 4020 arematched with the positions of mobile service data symbols each havingthe size of TDL, which are outputted from the input buffer 4011, so asto be in a one-to-one correspondence. Thereafter, the soft decisionvalues matched with the respective symbol position are inputted to thetrellis decoding unit 4012. At this point, since the main service datasymbols or the RS parity data symbols and known data symbols of the mainservice data do not correspond to the mobile service data symbols, thefeedback formatter 4021 inserts null data in the correspondingpositions, thereby outputting the processed data to the trellis decodingunit 4012. Additionally, each time the symbols having the size of TDLare turbo decoded, no value is fed-back by the symbol interleaver 4020starting from the beginning of the first decoding process. Therefore,the feedback formatter 4021 is controlled by the feedback controller4010, thereby inserting null data into all symbol positions including amobile service data symbol. Then, the processed data are outputted tothe trellis decoding unit 4012.

The output buffer 4022 receives the second soft decision value from thesymbol decoder 4018 based upon the control of the feedback controller4010. Then, the output buffer 4022 temporarily stores the receivedsecond soft decision value. Thereafter, the output buffer 4022 outputsthe second soft decision value to the RS frame decoder 2006. Forexample, the output buffer 4022 overwrites the second soft decisionvalue of the symbol decoder 4018 until the turbo decoding process isperformed for M number of times. Then, once all M number of turbodecoding processes is performed for a single TDL, the correspondingsecond soft decision value is outputted to the RS frame decoder 2006.

The feedback controller 4010 controls the number of turbo decoding andturbo decoding repetition processes of the overall block decoder, shownin FIG. 46. More specifically, once the turbo decoding process has beenrepeated for a predetermined number of times, the second soft decisionvalue of the symbol decoder 4018 is outputted to the RS frame decoder2006 through the output buffer 4022. Thus, the block decoding process ofa turbo block is completed. In the description of the present invention,this process is referred to as a regressive turbo decoding process forsimplicity.

At this point, the number of regressive turbo decoding rounds betweenthe trellis decoding unit 4012 and the symbol decoder 4018 may bedefined while taking into account hardware complexity and errorcorrection performance. Accordingly, if the number of rounds increases,the error correction performance may be enhanced. However, this may leadto a disadvantageous of the hardware becoming more complicated (orcomplex).

Meanwhile, the main service data processor 2008 corresponds to blockrequired for receiving the main service data. Therefore, theabove-mentioned blocks may not be necessary (or required) in thestructure of a digital broadcast receiving system for receiving mobileservice data only.

The data deinterleaver of the main service data processor 2008 performsan inverse process of the data interleaver included in the transmittingsystem. In other words, the data deinterleaver deinterleaves the mainservice data outputted from the block decoder 2005 and outputs thedeinterleaved main service data to the RS decoder. The data beinginputted to the data deinterleaver include main service data, as well asmobile service data, known data, RS parity data, and an MPEG header. Atthis point, among the inputted data, only the main service data and theRS parity data added to the main service data packet may be outputted tothe RS decoder. Also, all data outputted after the data derandomizer mayall be removed with the exception for the main service data. In theembodiment of the present invention, only the main service data and theRS parity data added to the main service data packet are inputted to theRS decoder.

The RS decoder performs a systematic RS decoding process on thedeinterleaved data and outputs the processed data to the dataderandomizer.

The data derandomizer receives the output of the RS decoder andgenerates a pseudo random data byte identical to that of the randomizerincluded in the digital broadcast transmitting system. Thereafter, thedata derandomizer performs a bitwise exclusive OR (XOR) operation on thegenerated pseudo random data byte, thereby inserting the MPEGsynchronization bytes to the beginning of each packet so as to outputthe data in 188-byte main service data packet units.

RS Frame Decoder

The data outputted from the block decoder 2005 are in portion units.More specifically, in the transmitting system, the RS frame is dividedinto several portions, and the mobile service data of each portion areassigned either to regions A/B/C/D within the data group or to any oneof regions A/B and regions C/D , thereby being transmitted to thereceiving system. Therefore, the RS frame decoder 2006 groups severalportions included in a parade so as to form an RS frame. Alternatively,the RS frame decoder 2006 may also group several portions included in aparade so as to form two RS frames. Thereafter, error correctiondecoding is performed in RS frame units.

For example, when the RS frame mode value is equal to ‘00’, then oneparade transmits one RS frame. At this point, one RS frame is dividedinto several portions, and the mobile service data of each portion areassigned to regions A/B/C/D of the corresponding data group, therebybeing transmitted. In this case, the RS frame decoder 2006 extractsmobile service data from regions A/B/C/D of the corresponding datagroup, as shown in FIG. 47( a). Subsequently, the RS frame decoder 2006may perform the process of forming (or creating) a portion on aplurality of data group within a parade, thereby forming severalportions. Then, the several portions of mobile service data may begrouped to form an RS frame. Herein, if stuffing bytes are added to thelast portion, the RS frame may be formed after removing the stuffingbyte.

In another example, when the RS frame mode value is equal to ‘01’, thenone parade transmits two RS frames (i.e., a primary RS frame and asecondary RS frame). At this point, a primary RS frame is divided intoseveral primary portions, and the mobile service data of each primaryportion are assigned to regions A/B of the corresponding data group,thereby being transmitted. Also, a secondary RS frame is divided intoseveral secondary portions, and the mobile service data of eachsecondary portion are assigned to regions C/D of the corresponding datagroup, thereby being transmitted.

In this case, the RS frame decoder 2006 extracts mobile service datafrom regions A/B of the corresponding data group, as shown in FIG. 47(b). Subsequently, the RS frame decoder 2006 may perform the process offorming (or creating) a primary portion on a plurality of data groupwithin a parade, thereby forming several primary portions. Then, theseveral primary portions of mobile service data may be grouped to form aprimary RS frame. Herein, if stuffing bytes are added to the lastprimary portion, the primary RS frame may be formed after removing thestuffing byte. Also, the RS frame decoder 2006 extracts mobile servicedata from regions C/D of the corresponding data group. Subsequently, theRS frame decoder 2006 may perform the process of forming (or creating) asecondary portion on a plurality of data group within a parade, therebyforming several secondary portions. Then, the several secondary portionsof mobile service data may be grouped to form a secondary RS frame.Herein, if stuffing bytes are added to the last secondary portion, thesecondary RS frame may be formed after removing the stuffing byte.

More specifically, the RS frame decoder 2006 receives the RS-encodedand/or CRC-encoded mobile service data of each portion from the blockdecoder 2005. Then, the RS frame decoder 2006 groups several portions,which are inputted based upon RS frame-associated information outputtedfrom the signaling decoder 2013 or the operation controller 2000,thereby performing error correction. By referring to the RS frame modevalue included in the RS frame-associated information, the RS framedecoder 2006 may form an RS frame and may also be informed of the numberof RS code parity data bytes and the code size. Herein, the RS code isused to configure (or form) the RS frame. The RS frame decoder 2006 alsorefers to the RS frame-associated information in order to perform aninverse process of the RS frame encoder, which is included in thetransmitting system, thereby correcting the errors within the RS frame.Thereafter, the RS frame decoder 2006 adds 1 MPEG synchronization databyte to the error-correction mobile service data packet. In an earlierprocess, the 1 MPEG synchronization data byte was removed from themobile service data packet during the RS frame encoding process.Finally, the RS frame decoder 2006 performs a derandomizing process onthe processed mobile service data packet.

FIG. 48 illustrates, when the RS frame mode value is equal to ‘00’, anexemplary process of grouping several portion being transmitted to aparade, thereby forming an RS frame and an RS frame reliability map.

More specifically, the RS frame decoder 2006 receives and groups aplurality of mobile service data bytes, so as to form an RS frame.According to the present invention, in transmitting system, the mobileservice data correspond to data RS-encoded in RS frame units. At thispoint, the mobile service data may already be error correction encoded(e.g., CRC-encoded). Alternatively, the error correction encodingprocess may be omitted.

It is assumed that, in the transmitting system, an RS frame having thesize of (N+2)×(187+P) bytes is divided into M number of portions, andthat the M number of mobile service data portions are assigned andtransmitted to regions A/B/C/D in M number of data groups, respectively.In this case, in the receiving system, each mobile service data portionis grouped, as shown in FIG. 48( a), thereby forming an RS frame havingthe size of (N+2)×(187+P) bytes. At this point, when stuffing bytes (S)are added to at least one portion included in the corresponding RS frameand then transmitted, the stuffing bytes are removed, therebyconfiguring an RS frame and an RS frame reliability map. For example, asshown in FIG. 27, when S number of stuffing bytes are added to thecorresponding portion, the S number of stuffing bytes are removed,thereby configuring the RS frame and the RS frame reliability map.

Herein, when it is assumed that the block decoder 2005 outputs a softdecision value for the decoding result, the RS frame decoder 2006 maydecide the ‘0’ and ‘1’ of the corresponding bit by using the codes ofthe soft decision value. 8 bits that are each decided as described aboveare grouped to create 1 data byte. If the above-described process isperformed on all soft decision values of several portions (or datagroups) included in a parade, the RS frame having the size of(N+2)×(187+P) bytes may be configured.

Additionally, the present invention uses the soft decision value notonly to configure the RS frame but also to configure a reliability map.

Herein, the reliability map indicates the reliability of thecorresponding data byte, which is configured by grouping 8 bits, the 8bits being decided by the codes of the soft decision value.

For example, when the absolute value of the soft decision value exceedsa pre-determined threshold value, the value of the corresponding bit,which is decided by the code of the corresponding soft decision value,is determined to be reliable. Conversely, when the absolute value of thesoft decision value does not exceed the pre-determined threshold value,the value of the corresponding bit is determined to be unreliable.Thereafter, if even a single bit among the 8 bits, which are decided bythe codes of the soft decision value and group to configure one databyte, is determined to be unreliable, the corresponding data byte ismarked on the reliability map as an unreliable data byte.

Herein, determining the reliability of one data byte is only exemplary.More specifically, when a plurality of data bytes (e.g., at least 4 databytes) are determined to be unreliable, the corresponding data bytes mayalso be marked as unreliable data bytes within the reliability map.Conversely, when all of the data bits within the one data byte aredetermined to be reliable (i.e., when the absolute value of the softdecision values of all 8 bits included in the one data byte exceed thepredetermined threshold value), the corresponding data byte is marked tobe a reliable data byte on the reliability map. Similarly, when aplurality of data bytes (e.g., at least 4 data bytes) are determined tobe reliable, the corresponding data bytes may also be marked as reliabledata bytes within the reliability map. The numbers proposed in theabove-described example are merely exemplary and, therefore, do notlimit the scope or spirit of the present invention.

The process of configuring the RS frame and the process of configuringthe reliability map both using the soft decision value may be performedat the same time. Herein, the reliability information within thereliability map is in a one-to-one correspondence with each byte withinthe RS frame. For example, if a RS frame has the size of (N+2)×(187+P)bytes, the reliability map is also configured to have the size of(N+2)×(187+P) bytes. FIG. 48( a′) and FIG. 48( b′) respectivelyillustrate the process steps of configuring the reliability mapaccording to the present invention.

Subsequently, the RS frame reliability map is used on the RS frames soas to perform error correction.

FIG. 49 illustrates example of the error correction processed accordingto embodiments of the present invention. FIG. 49 illustrates an exampleof performing an error correction process when the transmitting systemhas performed both RS encoding and CRC encoding processes on the RSframe.

As shown in FIG. 49( a) and FIG. 49( a′), when the RS frame having thesize of (N+2)×(187+P) bytes and the RS frame reliability map having thesize of (N+2)×(187+P) bytes are created, a CRC syndrome checking processis performed on the created RS frame, thereby verifying whether anyerror has occurred in each row. Subsequently, as shown in FIG. 49( b), a2-byte checksum is removed to configure an RS frame having the size ofN×(187+P) bytes. Herein, the presence (or existence) of an error isindicated on an error flag corresponding to each row. Similarly, sincethe portion of the reliability map corresponding to the CRC checksum hashardly any applicability, this portion is removed so that only N×(187+P)number of the reliability information bytes remain, as shown in FIG. 49(b′).

After performing the CRC syndrome checking process, as described above,a RS decoding process is performed in a column direction. Herein, a RSerasure correction process may be performed in accordance with thenumber of CRC error flags. More specifically, as shown in FIG. 49( c),the CRC error flag corresponding to each row within the RS frame isverified. Thereafter, the RS frame decoder 2006 determines whether thenumber of rows having a CRC error occurring therein is equal to orsmaller than the maximum number of errors on which the RS erasurecorrection may be performed, when performing the RS decoding process ina column direction. The maximum number of errors corresponds to P numberof parity bytes inserted when performing the RS encoding process. In theembodiment of the present invention, it is assumed that 48 parity byteshave been added to each column (i.e., P=48).

If the number of rows having the CRC errors occurring therein is smallerthan or equal to the maximum number of errors (i.e., 48 errors accordingto this embodiment) that can be corrected by the RS erasure decodingprocess, a (235,187)-RS erasure decoding process is performed in acolumn direction on the RS frame having (187+P) number of N-byte rows(i.e., 235 N-byte rows), as shown in FIG. 49( b). Thereafter, as shownin FIG. 49( e), the 48-byte parity data that have been added at the endof each column are removed. Conversely, however, if the number of rowshaving the CRC errors occurring therein is greater than the maximumnumber of errors (i.e., 48 errors) that can be corrected by the RSerasure decoding process, the RS erasure decoding process cannot beperformed. In this case, the error may be corrected by performing ageneral RS decoding process. In addition, the reliability map, which hasbeen created based upon the soft decision value along with the RS frame,may be used to further enhance the error correction ability (orperformance) of the present invention.

More specifically, the RS frame decoder 2006 compares the absolute valueof the soft decision value of the block decoder 2005 with thepre-determined threshold value, so as to determine the reliability ofthe bit value decided by the code of the corresponding soft decisionvalue. Also, bits, each being determined by the code of the softdecision value, are grouped to form one data byte. Accordingly, thereliability information on this one data byte is indicated on thereliability map. Therefore, as shown in FIG. 49( c), even though aparticular row is determined to have an error occurring therein basedupon a CRC syndrome checking process on the particular row, the presentinvention does not assume that all bytes included in the row have errorsoccurring therein. The present invention refers to the reliabilityinformation of the reliability map and sets only the bytes that havebeen determined to be unreliable as erroneous bytes. In other words,with disregard to whether or not a CRC error exists within thecorresponding row, only the bytes that are determined to be unreliablebased upon the reliability map are set as erasure points.

According to another method, when it is determined that CRC errors areincluded in the corresponding row, based upon the result of the CRCsyndrome checking result, only the bytes that are determined by thereliability map to be unreliable are set as errors. More specifically,only the bytes corresponding to the row that is determined to haveerrors included therein and being determined to be unreliable based uponthe reliability information, are set as the erasure points. Thereafter,if the number of error points for each column is smaller than or equalto the maximum number of errors (i.e., 48 errors) that can be correctedby the RS erasure decoding process, an RS erasure decoding process isperformed on the corresponding column. Conversely, if the number oferror points for each column is greater than the maximum number oferrors (i.e., 48 errors) that can be corrected by the RS erasuredecoding process, a general decoding process is performed on thecorresponding column.

More specifically, if the number of rows having CRC errors includedtherein is greater than the maximum number of errors (i.e., 48 errors)that can be corrected by the RS erasure decoding process, either an RSerasure decoding process or a general RS decoding process is performedon a column that is decided based upon the reliability information ofthe reliability map, in accordance with the number of erasure pointswithin the corresponding column. For example, it is assumed that thenumber of rows having CRC errors included therein within the RS frame isgreater than 48. And, it is also assumed that the number of erasurepoints decided based upon the reliability information of the reliabilitymap is indicated as 40 erasure points in the first column and as erasurepoints in the second column. In this case, a (235,187)-RS erasuredecoding process is performed on the first column. Alternatively, a(235,187)-RS decoding process is performed on the second column. Whenerror correction decoding is performed on all column directions withinthe RS frame by using the above-described process, the 48-byte paritydata which were added at the end of each column are removed, as shown inFIG. 49( e).

As described above, even though the total number of CRC errorscorresponding to each row within the RS frame is greater than themaximum number of errors that can be corrected by the RS erasuredecoding process, when the number of bytes determined to have a lowreliability level, based upon the reliability information on thereliability map within a particular column, while performing errorcorrection decoding on the particular column. Herein, the differencebetween the general RS decoding process and the RS erasure decodingprocess is the number of errors that can be corrected. Morespecifically, when performing the general RS decoding process, thenumber of errors corresponding to half of the number of parity bytes(i.e., (number of parity bytes)/2) that are inserted during the RSencoding process may be error corrected (e.g., 24 errors may becorrected). Alternatively, when performing the RS erasure decodingprocess, the number of errors corresponding to the number of paritybytes that are inserted during the RS encoding process may be errorcorrected (e.g., 48 errors may be corrected).

After performing the error correction decoding process, as describedabove, a RS frame configured of 187 N-byte rows (or packet) may beobtained as shown in FIG. 49( e). The RS frame having the size of N×187bytes is outputted by the order of N number of 187-byte units. At thispoint, 1 MPEG synchronization byte, which had been removed by thetransmitting system, is added to each 187-byte packet, as shown in FIG.49( f). Therefore, a 188-byte unit mobile service data packet isoutputted.

At this point, the RS frame decoded mobile service data is performed aderandomizing process, which corresponds to the inverse process of therandomizer included in the transmitting system and then the derandomizeddata are outputted, thereby obtaining the mobile service datatransmitted from the transmitting system. In the present invention, theRS frame decoder 2006 may perform the data derandomizing function.

An RS frame decoder may be configured of M number of RS frame decodersprovided in parallel, wherein the number of RS frame encoders is equalto the number of parades (=M) within an M/H frame, a multiplexer formultiplexing each portion and being provided to each input end of the Mnumber of RS frame decoders, and a demultiplexer for demultiplexing eachportion and being provided to each output end of the M number of RSframe decoders.

In the present invention, a parade refers to a collection of groupsbeing included in a single M/H frame. Herein, a parade transmits data ofone or two RS frames depending upon the respective RS frame mode. Also,an RS frame refers to a collection of multiple portions, and, dependingupon the respective RS frame mode, a portion is allocated to a partialregion within a data group. Since the RS frame mode has already beendescribed above in detail, the description of the same will be omittedherein for simplicity.

Furthermore, data groups for multiple parades may be allocated to oneM/H frame.

FIG. 50 illustrates an example where to parades (Parade #0 and Parade#1) are allocated to a single M/H frame, thereby being transmitted. Forexample, if the first parade (Parade #0) transmits one RS frame, and if3 data groups are included for each sub-frame, the position of each datagroup within the corresponding sub-frame may be obtained by substitutingthe value i in Equation 1 shown above with values ranging from 0 to 2.More specifically, the data groups of the first parade (Parade #0) aresequentially allocated to a first slot, a fifth slot, and a ninth slot(Slot #0, Slot #4, and Slot #8) within the sub-frame. In this case, NOGis equal to ‘3’ (i.e., NOG=3), and the RS frame mode value is equal to‘00’.

Also, if the second parade (Parade #1) transmits one RS frame, and if 2data groups are included for each sub-frame, the position of each datagroup within the corresponding sub-frame may be obtained by substitutingthe value i in Equation 1 shown above with values ranging from 3 to 4.More specifically, the data groups of the second parade (Parade #0) aresequentially allocated to a second slot and a twelfth slot (Slot #1 andSlot #11) within the sub-frame. In this case, NOG is equal to ‘2’ (i.e.,NOG=2), and the RS frame mode value is equal to ‘00’.

At this point, it is assumed that a mobile service included in the RSframe that is being received in the first parade (Parade #0) is providedto the user. In this case, the block decoder 2005 performsblock-decoding on each portion allocated to the data groups of the firstparade (Parade #0), thereby outputting the block-decoded portions to theRS frame decoder 2006. The RS frame decoder 2006 collects data ofmultiple portions being inputted therein depending upon the informationrelated to the RS frame being outputted from the operation controller2000 (or the signaling decoder 2013), thereby configuring the RS frameof the first parade (Parade #0). According to an embodiment of thepresent invention, when configuring the RS frame, a reliability mapindicating whether each data byte within the RS frame is reliable or notis generated. Since the method of generating the reliability map hasalready been described above, the detailed description of the same willbe omitted for simplicity.

Thereafter, errors occurring in the RS frame may be corrected byperforming CRC-decoding and RS-decoding on the RS frame of the firstparade (Parade #0). The error-corrected RS frame includes mobile servicedata for at least one or more mobile services. And, mobile service datafor the mobile service selected by the user or the system areaudio-/video-decoded, thereby being provided to the user.

In the meantime, while the mobile service (or services) included in theRS frame, which is received by the first parade (Parade #0), is beingprovided to the user, if the user or system selects a mobile serviceincluded in an RS frame being received by the second parade (Parade #1),a parade change command is generated. More specifically, the paradechange command may be generated by a channel-switching, reservedviewing, reserved recording, and so on.

Accordingly, the data groups of the second parade

(Parade #1) are received by the tuner 1301, demodulator 2002, and theequalizer 2003 within the receiving system. Thereafter, the receiveddata groups are demodulated and channel-equalized, thereby beingoutputted to the block decoder 2005. The block decoder 2005 performsblock-decoding on each portion allocated to the data groups of thesecond parade (Parade #1), thereby outputting the block-decoded portionsto the RS frame decoder 2006. The RS frame decoder 2006 collects data ofmultiple portions being inputted therein depending upon the informationrelated to the RS frame being outputted from the operation controller2000 (or the signaling decoder 2013), thereby configuring the RS frameof the second parade (Parade #1).

For example, it is assumed that the RS frame being received by thesecond parade (Parade #1) corresponds to an RS frame having the size of(N+2)×235 bytes, wherein 2 bytes of CRC data are added to each row of anRS frame payload having the size of N×187 bytes, and wherein 48 bytes ofRS parity data are added to each column of the RS frame payload. It isalso assumed that the RS frame having the size of (N+2)×235 bytes isdivided into 10 portions, that the data of the 10 portions (i.e., dataincluding mobile service data, CRC data, RS parity data within thecorresponding RS frame) are allocated to regions A/B/C/D of 10respective data groups, and also that 2 of the 10 data groups areallocated to each sub-frame, as shown in FIG. 50, thereby beingtransmitted.

In this case, the block decoder 2005 performs block-decoding on the dataof the 10 portions allocated to regions A/B/C/D of the 10 data groups.Thereafter, the RS frame decoder 2006 configures the RS frame having thesize of (N+2)×235 bytes by collecting data of the 10 portions.Subsequently, the RS frame decoder 2006 performs CRC-decoding on theconfigured RS frame (i.e., performs a CRC syndrome check process) so asto verify whether any error exists in each row, thereby indicating theexistence of an error on a CRC error flag respective to each row. Afterperforming the CRC-decoding process, the RS frame decoder 2006 removesthe 2-byte CRC data from the RS frame.

FIG. 51 illustrates an exemplary RS frame configuration, when the RSframe is configured by collecting data of 10 portions, and when the2-byte CRC data are removed from the RS frame after performingCRC-decoding. The number of data byes in each portion shown in FIG. 51is merely exemplary and given to facilitate the understanding of thepresent invention. Therefore, the scope and spirit of the presentinvention will not be limited only to the numbers given in thedescription of the present invention.

Also, as shown in FIG. 51, one of a general RS-decoding process and anRS-erasure decoding process is performed on each of column of the RSframe having the CRC data removed therefrom, thereby correcting theerrors occurred in the RS frame. More specifically, one of the generalRS-decoding process and the RS-erasure decoding process is selecteddepending upon the number of CRC errors existing in the RS frame andalso depending upon the reliability information of the reliability map.Herein, according to an embodiment of the present invention, the numberof CRC errors is estimated by counting the number of CRC error flagsindicating the presence of an error among the total CRC error flagscorresponding to each row. The RS frame having its errors corrected byRS-decoding includes mobile service data for at least one or more mobileservices, and the mobile service data for the at least one or moremobile services selected by the user or the system areaudio-/video-decoded, thereby being provided to the user.

At this point, the parade change command may be generated at any pointwithin the M/H frame. For example, if a parade change command ordering achange from the first parade (Parade #0) to the second parade (Parade#1) is generated from point A, as shown in FIG. 50, the first data groupof the second parade (Parade #1) has already passed chronologically. Inthis case, if the RS frame is configured starting from the second datagroups being received by the current M/H frame, the data of the portionallocated to the first data group are omitted, thereby causing the RSframe configuration to be incomplete. However, of the system waits untilthe next M/H frame is received, so as to configure the RS frame startingfrom the data groups of the second parade (Parade #1) of the next M/Hframe, an excessive amount of time, which corresponds to the waitingtime, is wasted. Thus, a respective time delay may be caused whenperforming a channel-switching process, wherein the parade is changed(or changed). Such time delay eventually leads to an inconvenience forthe user.

Therefore, in order to resolve such disadvantage, in the presentinvention, when a parade change command is generated at the startingpoint of the M/H frame, the current M/H frame, from which the paradechange command has been generated, receives the data groups of thechange-designated parade, thereby configuring the RS frame. At thispoint, according to an embodiment of the present invention, if datagroups incapable of receiving data occur, when configuring the RS frame,null data are allocated to the data positions of the portion, which isallocated to the corresponding data group that is incapable of receivingdata. Thus, the RS frame configuration is completed.

Herein, the null data may be given a pre-decided value, an arbitraryvalue, or a specific value. Alternatively, the null data may be giventhe value of ‘0’ or ‘1’. Also, according to the embodiment of thepresent invention, when performing the CRC-decoding process on the RSframe, the CRC error flag corresponding to the row including the nulldata indicates the existence of the error in the corresponding row,thereby performing RS-decoding. For example, when the CRC error flagvalue is equal to ‘0’, this indicates that no error exists.Alternatively, when the CRC error flag value is equal to ‘1’, thisindicates that an error exists in the corresponding row.

Also, according to the embodiment of the present invention, whengenerating a reliability map that indicates reliability levels of eachdata byte within the RS frame, the reliability information correspondingto the null data byte within the reliability map is indicated asunreliable (or having no reliability).

More specifically, the information related to the RS frame, which isprovided from the operation controller 2000 to the RS frame decoder2006, not only include information for configuring the corresponding RSframe but also includes information on the data group including the datathat are currently being received. Therefore, the RS frame decoder 2006configures the RS frame, as shown in FIG. 51, based upon suchinformation related to the RS frame. At this point, the accurate datapositions of each data group may also be known.

Accordingly, when a parade change command is generated from point A ofFIG. 50, the RS frame is configured starting from the data group beingreceived after point A (i.e., starting from the data of the portionsallocated to the second data group). Also, null data are written in theposition corresponding to the data of the portion allocated to the firstdata group.

Referring to FIG. 52, the area marked with slanted lines corresponds tothe portion allocated to the first data group of the second parade(Parade #1), and null data are written in this area when configuring theRS frame. Also, when performing CRC-decoding, the CRC error flag of therow including the null data indicates the existence of an error. In FIG.52, when it is assumed that no error is included in any other datagroup, 24 CRC error flags respectively indicate the existence of anerror.

In the example shown in FIG. 52, it can be known that the occupationrate of the portion allocated to the first data group within therespective RS frame corresponds to 10% of the entire RS frame.Therefore, even though the CRC error flag of each row including the dataof the portion allocated to the first data group indicates the existenceof an error, if it is verified that there are no error in other datagroups, all data of the portions that have not been received (i.e.,non-received portions) during the RS-decoding of the RS frame may berecovered regardless of the RS code mode.

However, when a parade change command is generated from point B of FIG.50, the RS frame is configured starting from the data group beingreceived after point B (i.e., starting from the data of the portionsallocated to the third data group). Also, null data are written in theposition corresponding to the data of the portions allocated to thefirst data group and the second data group.

Referring to FIG. 53, the area marked with slanted lines corresponds tothe portions allocated to the first and second data groups of the secondparade (Parade #1), and null data are written in this area whenconfiguring the RS frame. Also, when performing CRC-decoding, the CRCerror flag of the row including the null data indicates the existence ofan error. In FIG. 53, when it is assumed that no error is included inany other data group, 48 CRC error flags respectively indicate theexistence of an error.

At this point, when it is assumed that the RS code mode is equal to ‘10’(i.e., when the number of RS parities added to the corresponding RSframe is equal to 48), even though the CRC error flag of each rowincluding the data of the portions allocated to the first and seconddata groups indicates the existence of an error, if it is verified thatthere are no error in other data groups, all data of the portions thathave not been received during the RS-decoding of the RS frame may berecovered regardless of the RS code mode.

As described above, when a parade change command is generated, an RSframe is configured by writing null data in positions for data of theportion allocated to the non-received data group. Then, when performingCRC-decoding on the RS frame, the CRC error flag of each row includingthe null data indicates the existence of an error. Thereafter, the RSdecoding process is performed. At this point, if the number of CRCerrors within the RS frame is less than or equal to the number of RSparity data bytes added to each column of the corresponding RS frame,the data of the non-received portion may all be recovered.

Therefore, when the parade change command is generated at the startingpoint of the M/H frame (e.g., at the point where the first data group orthe second data group is received), the present invention mayimmediately provide a respective mobile service to the user withouthaving to wait until the next M/H frame, wherein the mobile service isincluded in the RS frame being received in the change-designated parade(i.e., the designated parade to which the initial parade is to bechanged). More specifically, the channel-switching time may be reduced.

According to an embodiment of the present invention, when the paradechange command is generated within the first sub-frame of the M/H frame,the RS frame may be configured from the data groups that are beingreceived to the change-designated parade of the current M/H frame,thereby performing CRC-decoding and RS-decoding. More specifically, whenthe parade change command is generated in sub-frames within the M/Hframe excluding the first sub-frame, the system waits until the next M/Hframe. Thereafter, the system receives the data groups of thechange-designated parade of the next M/H frame, thereby performingCRC-decoding and RS-decoding.

FIG. 54 illustrates a flow chart showing the RS frame decoding processaccording to an embodiment of the present invention. Herein, FIG. 54shows an example of the RS frame decoding process, when a parade changecommand designating a parade change from the first parade (Parade #0) tothe second parade (Parade #1). More specifically, when a parade changecommand designating a parade change from the first parade (Parade #0) tothe second parade (Parade #1) is generated (S6011), the systemdetermines whether the point of generation of the parade change commandis within the first sub-frame of the current M/H frame (S6012). If it isdetermined that the command generation point is within the firstsub-frame, the system receives data groups of the second parade in thecurrent M/H frame (S6013). Meanwhile, if it is determined that thecommand generation point is not within the first sub-frame, the systemwaits until the next M/H frame, so as to receive data groups of thesecond parade in the next M/H frame (S6014). The above-described errorcorrection decoding process may be directly used without modification asthe process steps subsequent to step 6014.

For example, when it is assumed that a parade change command designatinga parade change from the first parade (Parade #0) to the second parade(Parade #1) is generated in point A, as shown in FIG. 50, the systemreceives data from the second data group of the second parade within thecurrent M/H frame, thereby performing demodulation andchannel-equalization on the received data group (S6015). Subsequently,the system performs block-decoding on the portion allocated to thechannel-equalized data group (S6016). When the block-decoding process isperformed on each portion of all data groups within the second parade,which is received in the current M/H frame, the system collects the dataof each portion so as to configure an RS frame (S6017). At this point,null data are written in the data position of the non-received portion(i.e., data position of the portion allocated to the first data group),thereby configuring the RS frame. Also, when performing CRC-decoding onthe RS frame configured as described above, the CRC error flags of eachrow including the null data indicate the existence of an error (S6018).

After performing the CRC-decoding process, the system counts the numberof CRC error flags indicating the existence of an error in the RS frame,thereby obtaining the CRC errors (S6019). At this point, depending uponthe number of CRC errors, a general RS decoding process may be performedon each column or an RS erasure decoding process may be performed oneach column. When deciding which one of the general RS decoding processand the RS erasure decoding process to perform, the present inventionmay refer to the reliability information of the reliability map.

If the number of CRC errors is less than or equal to a maximum number oferrors correctable by RS erasure decoding, the system performs RSerasure decoding on all columns of the RS frame (S6020). The maximumnumber of errors corresponds to a number of RS parity bytes (P) thathave been inserted during the RS encoding process. Herein, the number ofRS parity bytes (P) may vary depending upon the RS code mode value.According to an embodiment of the present invention, it is assumed thatthe number of parity bytes (P) being added for to column is equal to 48(i.e., the RS code mode value is equal to ‘10’). For example, if thesize of an RS frame that is to be RS-decoded is equal to N×235, in step6020, a (235,187)-RS erasure decoding process is performed in a columndirection on the RS frame having (187+P) number of N-byte rows (i.e.,235 N-byte rows). Thereafter, the 48 bytes of parity data that wereadded at the end of each column are removed.

Meanwhile, if the number of CRC errors is greater than a maximum numberof errors correctable by RS erasure decoding, the system cannot performRS erasure decoding on all columns of the RS frame. In this case, errorcorrection may be performed by using the general RS decoding process.Also, the present invention may use the reliability map, which wascreated when configuring the RS frame, thereby enhancing the errorcorrection performance.

For example, in a row having CRC errors, only the data bytes marked tobe unreliable (or non-reliable) are respectively set as erasure points.Thereafter, for each column, if the number of erasure points (i.e.,errors) is less than or equal to the maximum number of errorscorrectable by RS erasure decoding (i.e., 48 errors correctable by RSerasure decoding), the system performs RS erasure decoding on therespective column (S6021). Alternatively, for each column, if the numberof erasure points (i.e., errors) is greater than to the maximum numberof errors correctable by RS erasure decoding (i.e., 48 errorscorrectable by RS erasure decoding), the system performs generalRS-decoding on the respective column.

More specifically, for example, it is assumed that the total number ofCRC errors of the RS frame is greater than 48. Herein, the total numberof CRC errors comprises CRC errors indicated on CRC error flags of eachrow including the data of portions allocated to the first data group,which is not received in the RS frame. Herein, it is also assumed that40 erasure points are marked in the first column and that 50 erasurepoints are marked in the second column. Herein, the number of erasurepoints is decided by the reliability information of the reliability map.Accordingly, (235,187)-RS erasure decoding is performed on the firstcolumn, and (235,187)-RS decoding is performed on the second column.When error correction decoding is performed on all columns within the RSframe by performing the above-described process, the 48 bytes of paritydata that were added at the end of each column are removed.

After performing error correction decoding, as described above, thesystem may obtain an RS frame having the size of N×187 bytes (S6022).Herein, the RS frame having the size of N×187 bytes is sequentiallyoutputted in N number of 187-byte units (or packets). At this point, a 1byte of MPEG synchronization byte, which had been deleted by thetransmitting system, is added to each 187-byte packet, therebyoutputting a mobile service data packet of 188 bytes. As describedabove, the RS-decoded mobile service data are derandomized, as aninverse process of the randomizer included in the transmitting system,thereby being outputted. Thus, the mobile service data transmitted bythe transmitting system may be obtained.

When a parade change command is generated in a sub-frame other than thefirst sub-frame, the present invention no longer receives any furtherdata groups and waits until the next M/H frame. Thereafter, the presentinvention receives the data groups of a change-designated parade in thenext M/H frame, thereby configuring the RS frame. Therefore, even whenthe parade change command is generated in the last sub-frame, thepresent invention no longer receives any further data groups in thecurrent M/H frame and waits until the next M/H frame. However, the datagroups of the previous parade are received until the generation point ofthe parade change command and are also demodulated and decodedaccordingly.

For example, as shown in FIG. 55, when a parade change command orderinga change from the first parade (Parade #0) to the second parade (Parade#1) is generated from point C, the data groups of the first parade areno longer received. Subsequently, the system waits until point D so asto receive data groups of the second parade starting from point D. Then,the system performs demodulating, channel-equalizing, block-decodingprocess of the received data groups of the second parade, therebyconfiguring the RS frame. After performing CRC-decoding and RS-decodingon the RS frame, the mobile service included in the processed RS frameis provided to the user. However, in point C, wherein the parade changecommand has been generated, among the total of 15 data groupscorresponding to the first parade, 13 groups have already been received.

Therefore, according to an embodiment of the present invention, in thiscase, instead of discarding (or deleting) the 13 data groups of thecurrent M/H frame without processing, the present invention furtherreceives the remaining two data groups of the current M/H frame, so asto configure the RS frame of the first parade. Then, the presentinvention receives the data groups of the second parade in the next M/Hframe, so as to configure the RS frame of the second parade. In thiscase, the mobile service included in the RS frame of the first parade isprovided to the user until the end of the current M/H frame. Then, themobile service included in the RS frame of the second parade is providedto the user starting from the next M/H frame. Thus, the presentinvention becomes advantageous in that the user may be provided withuninterrupted mobile services.

According to another embodiment of the present invention, when thepresent invention is unable to receive the remaining two data groups ofthe current M/H frame, null data are written in the data positions ofthe portions allocated to the two non-received data groups, therebyconfiguring the RS frame. Thereafter, when performing CRC-decoding onthe RS frame, CRC error flags of each row including the null dataindicate the existence of an error, thereby performing RS-decoding.Depending upon the number of CRC errors, and also depending upon thereliability information of the reliability map, one of a generalRS-decoding process and a RS erasure decoding process may be used as theRS-decoding process.

If there are no errors in the other data groups, and if the number ofrows including the null data are less than or equal to the maximumnumber of errors correctable by RS erasure decoding, the data of theportions of the two non-received data groups may be fully recoveredduring the RS decoding process of the RS frame. In this case also, themobile service included in the RS frame of the first parade is providedto the user until the end of the current M/H frame. Then, the mobileservice included in the RS frame of the second parade is provided to theuser starting from the next M/H frame. Thus, the present inventionbecomes advantageous in that the user may be provided with uninterruptedmobile services.

Meanwhile, among the data groups received through a parade, even whensome data groups are not received (or unable to be received) dependingupon the condition of the receiving system, the present invention mayconfigure the RS frame by using the above-described method, therebyperforming CRC-decoding and RS-decoding. For example, as shown in FIG.56, it is assumed that the present invention successfully receives thefirst to 4^(th) data groups, then fails to receive the 5^(th) data groupdue to poor reception, and finally resumes successful reception startingfrom the 6^(th) data group.

In this case also, null data are written in the data position of theportion allocated to the 5^(th) data group. Then, the portion data ofall of the data groups excluding the 5^(th) data group are collected, soas to configure the RS frame. Also, when performing CRC-decoding, CRCerror flags of each row including the null data indicate the existenceof an error. Referring to FIG. 56, when it is assumed that there are noerrors in the other data groups, 24 CRC error flags respectivelyindicate the existence of an error.

Therefore, even when the CRC error flags of each row including data ofthe portion allocated to the 5^(th) data group respectively indicate theexistence of an error, if there are no error in the other data groups,regardless of the RS code mode, the data of the non-received portionsmay be fully recovered when performing RS-decoding (i.e., RS erasuredecoding) of the RS frame. Also, when 2 data groups are non-received,and the number of rows including the data of the portions allocated tothe 2 data groups is less than or equal to 48, and when the RS code modeis equal to ‘10’ (i.e., 48), and when there are no error in the otherdata groups, in this case also, RS erasure decoding is performed on allcolumns, thereby being able to fully recover the data of the portionsallocated to the 2 non-received data groups.

As described above, the digital broadcasting system and the method forprocessing a broadcast signal have the following advantages. Morespecifically, the digital broadcasting system and the method forprocessing a broadcast signal according to the present invention arerobust (or strong) against any error that may occur when transmittingmobile service data through a channel. And, the present invention isalso highly compatible to the conventional receiving system. Moreover,the present invention may also receive the mobile service data withoutany error occurring, even in channels having severe ghost effect andnoise.

When a parade change command is generated at the starting portion of thecurrent M/H frame, the current M/H frame receives data groups of achange-designated parade, so as to configure the RS frame. At thispoint, null data are inserted in data positions of portions allocated tothe non-received data groups, thereby configuring the RS frame. Then,when performing CRC-decoding, the CRC error flags of each row includingthe null data respectively indicate the existence of an error, therebyperforming RS-decoding. Thus, when the parade change command isgenerated, the parade change is immediately performed without having towait until the next M/H frame. Thus, the channel-switching timeaccording to the parade change may be reduced.

When a parade change command is generated at the ending portion of thecurrent M/H frame, the RS frame is configured with data groups of apreviously received parade in the current M/H frame. At this point, whenperforming CRC-decoding, the CRC error flags of each row including thenull data respectively indicate the existence of an error, therebyperforming RS-decoding. Thus, when the parade change command isgenerated, the present invention may provide the user with a mobileservice included in the RS frame of a previous parade during the currentM/H frame. And, the present invention may provide the user with a mobileservice included in the RS frame of a changed parade starting from thenext M/H frame. Thus, the present invention may provide the user withuninterrupted mobile services.

Finally, the present invention is even more effective when applied tomobile and portable receivers, which are also liable to frequent changein channels, and which require strength (or robustness) against intensenoise.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A receiving system, comprising: a signal receiving unit, when aparade change command ordering parade change from a first parade to asecond parade is generated, receiving a broadcast signal including datagroups of the second parade starting from a generation point of theparade change command, while receiving the broadcast signal including atransmission frame transmitting the first and second parades; asignaling decoder decoding signaling information included in the datagroups and outputting RS frame-related information; a block decoderperforming turbo-decoding in block units on data of a portion includedin the data groups; and an RS frame decoder inserting null data in datapositions of a portion included in non-received data group within an RSframe of the second parade, while configuring the RS frame of the secondparade by collecting data of the turbo-decoded portions based upon theRS frame-related information, performing CRC-decoding by indicating theexistence of errors on CRC error flags of each row including the nulldata within the RS frame, and performing RS-decoding on the CRC-decodedRS frame.
 2. The receiving system of claim 1, wherein the RS framedecoder counts a number of CRC error flags indicating the existence ofan error, among the CRC error flags corresponding to each row within theRS frame, thereby estimating a number of CRC errors.
 3. The receivingsystem of claim 2, wherein the RS frame decoder generates a reliabilitymap indicating reliability information on each data within the RS frame,and wherein the reliability information corresponding to the null datais marked to be unreliable.
 4. The receiving system of claim 3, wherein,when the number of CRC errors is less than or equal to a maximum numberof errors correctable by RS erasure decoding, the RS frame decoderperforms RS erasure decoding on all columns of the RS frame.
 5. Thereceiving system of claim 3, wherein, when the number of CRC errors isgreater than a maximum number of errors correctable by RS erasuredecoding, the RS frame decoder refers to the reliability information ofthe reliability map, and performs any one of general RS-decoding and RSerasure decoding for each column of the RS frame.
 6. The receivingsystem of claim 1, wherein, when the parade change command ordering theparade change from the first parade to the second parade is generated,the signal receiving unit receives a broadcast signal including datagroups of the second parade from a next transmission frame.
 7. Thereceiving system of claim 6, wherein the RS frame decoder collects dataof a portion included in data groups of the first parade, the firstparade being received until the generation point of the parade changecommand and being turbo-decoded, so as to configure an RS frame, andinserts null data in data positions of a portion included innon-received data groups within the RS frame of the first parade.
 8. Thereceiving system of claim 6, wherein the RS frame decoder performsCRC-decoding by indicating the existence of errors on CRC error flags ofeach row including the null data within the RS frame of the firstparade, and performs RS-decoding on the CRC-decoded RS frame.
 9. Amethod for processing a broadcast signal of a receiving system,comprising: when a parade change command ordering parade change from afirst parade to a second parade is generated, receiving a broadcastsignal including data groups of the second parade starting from ageneration point of the parade change command, while receiving thebroadcast signal including a transmission frame transmitting the firstand second parades; decoding signaling information included in the datagroups and outputting RS frame-related information; performingturbo-decoding in block units on data of a portion included in the datagroups; and inserting null data in data positions of a portion includedin non-received data group within an RS frame of the second parade,while configuring the RS frame of the second parade by collecting dataof the turbo-decoded portions based upon the RS frame-relatedinformation, performing CRC-decoding by indicating the existence oferrors on CRC error flags of each row including the null data within theRS frame, and performing RS-decoding on the CRC-decoded RS frame. 10.The method of claim 9, wherein, in the decoding signaling information, anumber of CRC error flags indicating the existence of an error iscounted, among the CRC error flags corresponding to each row within theRS frame, thereby estimating a number of CRC errors.
 11. The method ofclaim 10, wherein the configuring the RS frame further includes a stepof generating a reliability map indicating reliability information oneach data within the RS frame, and wherein the reliability informationcorresponding to the null data is marked to be unreliable.
 12. Themethod of claim 11, wherein, when the number of CRC errors is less thanor equal to a maximum number of errors correctable by RS erasuredecoding, RS erasure decoding is performed on all columns of the RSframe.
 13. The method of claim 11, wherein, when the number of CRCerrors is greater than a maximum number of errors correctable by RSerasure decoding, the reliability information of the reliability map isreferred to so as to perform any one of general RS-decoding and RSerasure decoding for each column of the RS frame.
 14. The method ofclaim 9, further comprising: receiving a broadcast signal including datagroups of the second parade from a next transmission frame, when theparade change command ordering the parade change from the first paradeto the second parade is generated.
 15. The method of claim 14, whereinconfiguring the RS frame collects data of a portion included in datagroups of the first parade, the first parade being received until thegeneration point of the parade change command and being turbo-decoded,so as to configure an RS frame, and inserts null data in data positionsof a portion included in non-received data groups within the RS frame ofthe first parade.
 16. The method of claim 15, further comprising:performing CRC-decoding by indicating the existence of errors on CRCerror flags of each row including the null data within the RS frame ofthe first parade; and performing RS-decoding on the CRC-decoded RSframe.